Effect of insulin on uric acid excretion in humans

The role of hyperuricemia in the progression of end-stage kidney disease and its molecular prospective in inflammation and cardiovascular diseases: A general review

With the ongoing development of the Chinese economy, the occurrence of chronic kidney disease (CKD) has experienced a remarkable upsurge recently, and due to uremia caused by CKD, the number of patients undergoing dialysis has shown a dramatic increase. China has been ranked first in the world for patients undergoing hemodialysis (HD) and peritoneal dialysis (PD) with approximately one million patients across the country. Due to the loss of kidney function caused by CKD, the kidneys tend to lose their ability to excrete uric acid (UA) out of the body; therefore, most patients undergoing dialysis are complicated with hyperuricemia (HUA). HUA is an abnormal disease of purine metabolism, and it's considered a chronic disease. More than 90% of patients suffering from HUA will not show any symptoms on physical examination. According to statistics, if high serum UA is left untreated, 55% of patients will develop severe problems due to the purine crystallization in the body, and the kidneys are the most affected organs by HUA causing renal insufficiency that can promote end-stage kidney disease (ESKD) by activating the renin-angiotensin system (RAS), which will lead to inflammation, arteriosclerosis, cardiovascular diseases (CVD), and other diseases. Lifestyle modifications and pharmacological interventions are the first primary choice for lowering UA, although dialysis will tend to reduce the high UA levels in the blood, drugs are also necessary. This review will summarize the mechanisms and metabolism of UA, the relationship between HUA and ESKD progression, HUA and inflammation, HUA and CVD, and pharmacological treatment of HUA.

Association between serum uric acid levels and arterial stiffness in patients with psoriasis

This study examined the association between serum uric acid levels (SUA) and arterial stiffness in patients with psoriasis vulgaris. A cross-sectional study was conducted on 205 consecutive patients with psoriasis vulgaris who visited the Dermatology Clinic of China-Japan Friendship Hospital between March 2022 and July 2024. Arterial stiffness was assessed by measuring brachial-ankle pulse wave velocity (baPWV). The patients were divided into four groups (Q1, Q2, Q3, and Q4) according to the quartiles of SUA levels. The clinical data of each group were analysed and compared. Multivariate linear regression was employed to investigate the linear correlation between SUA levels and baPWV, and subgroup analyses were performed. There were differences in sex ratio, body mass index (BMI), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), homocysteine (HCY), and baPWV levels between the four groups. After adjustment for confounders, a significant linear correlation between SUA and baPWV remained, with baPWV increasing by 0.519 cm/s for every 1 mmol/L increase in SUA (β=0.519, 95%CI: 0.176-0.862, P = 0.003). BaPWV was significantly higher in the Q4 group compared with the lowest Q1 group (β=137.043, 95%CI: 43.574-230.511, P = 0.004). Subgroup analysis showed that the positive correlation between SUA and baPWV was more significant in the subgroups of males, moderate-to-severe psoriasis, no history of hypertension, no history of hyperlipidaemia, non-smokers and BMI ≥ 24 kg/m2. In patients with psoriasis, high SUA is associated with increased baPWV. Early screening and intervention of cardiovascular risk should be emphasised. Further studies are needed to establish a causal relationship and to guide treatment.

The impact of uric acid on musculoskeletal diseases: clinical associations and underlying mechanisms

Serum urate (SU) levels are significantly elevated in conditions such as gout, type 2 diabetes (T2D), obesity, and other metabolic syndromes. Recently, due to the high prevalence of hyperuricemia (HUA), numerous clinical connections between SU and musculoskeletal disorders like sarcopenia, osteoarthritis (OA), rheumatoid arthritis (RA), intervertebral disc degeneration (IDD), and osteoporosis (OP) have been identified. This review discusses the mechanisms linking SU to musculoskeletal disorders, as well as the clinical associations of SU with conditions such as sarcopenia, T2D with sarcopenia, McArdle disease, heart failure, gout, OA, IDD, OP and exercise-induced acute kidney injury (EIAKI), offering valuable insights for improved prevention and treatment strategies. Mechanisms linking SU to musculoskeletal disorders include oxidative stress, MSU (monosodium urate) crystal deposition, inflammation, and other factors. In adults, both age and SU levels should be considered for preventing sarcopenia, while gender and SU may directly impact muscle mass in children and adolescents. HUA and gout may be risk factors for OA progression, although some reports suggest otherwise. A U-shaped relationship between SU and IDD has been reported, particularly in Chinese men, indicating lower or higher SU level may be risk factors for IDD. Maintaining SU levels within a certain range may help prevent OP and fractures. Future research, including epidemiological studies and new pathogenesis findings, will further clarify the relationship between musculoskeletal diseases and SU.

High Fat Mass Index is Associated with Endometrial Hyperplasia in Polycystic Ovary Syndrome Patients: A Retrospective Study

Aim

To assess body composition, glucolipid metabolism, and uric acid levels in PCOS (Polycystic Ovary Syndrome) patients to determine their relationship with the risk of endometrial hyperplasia (EH).

Methods

A total of 232 patients were included and divided into groups according to whether they had PCOS and endometrial pathology (Group A: non-PCOS and normal endometrium; Group B: PCOS and normal endometrium; Group C: non-PCOS and EH; Group D: PCOS and EH). Body composition differences between groups and correlations between body composition, glucolipid metabolism, and uric acid levels were analyzed.

Results

In Group D, the patient's PSM (Percent Skeletal Muscle) of Trunk, PBF (Percent Body Fat) of Arm, free mass index, FMI (Fat Mass Index), and appendicular skeletal muscle mass index were significantly higher than in Groups A, B, and C. Waist-hip rate, PBF, PBF of Trunk, PSM of Leg, skeletal muscle mass index and visceral fat level were significantly higher than in Groups A and B. FMI was an independent risk factor for EH in PCOS patients, the AUC for FMI prediction of endometrial hyperplasia in PCOS patients was 0.82. FMI had significant positive correlations with fasting glucose, fasting insulin, HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), total cholesterol, triglyceride, low-density lipoprotein, triglyceride/high-density lipoprotein, and uric acid levels. FMI was correlated with HOMA-IR and uric acid at 0.602 and 0.649 respectively in PCOS patients.

Conclusion

Increased FMI and altered glucolipid metabolism as key factors associated with a higher risk of EH in patients with PCOS. Monitoring body composition and metabolic health in PCOS patients could help identify those at greater risk of EH, guiding preventive interventions.

Threshold effect of atherogenic index of plasma on type 2 diabetes mellitus and modification by uric acid in normal-weight adults with hypertension

Background

The association between atherogenic index of plasma (AIP) and type 2 diabetes mellitus (T2DM) in normal-weight individuals with hypertension remains unclear. This study seeks to elucidate this relationship in normal-weight adults with hypertension.

Methods

This cross-sectional study included 8,258 normal-weight adults with hypertension from the China Hypertension Registry Study. The AIP was calculated as log10 (triglycerides/high-density lipoprotein cholesterol). The multivariate logistic regression, generalized additive model, smooth fitting curve, sensitivity analyses, two-part logistic regression, and subgroup analyses were conducted to detect the correlation between AIP and T2DM.

Results

The mean age of the study population was 64.89 ± 8.97 years, with an overall prevalence of T2DM of 15.55%. Multivariate logistic regression analyses indicated that there was a positive and independent relationship between AIP and T2DM (OR: 3.73; 95% CI: 2.82, 4.94). Threshold effect analysis identified a J-shaped association between AIP and T2DM, with an inflection point at 0. Additionally, an interaction between hyperuricemia and AIP was observed (P for interaction = 0.034).

Conclusions

In normal-weight adults with hypertension, there was a J-shaped association between AIP and T2DM, with an inflection point at 0. the correlation between AIP and T2DM was more pronounced in individuals with hyperuricemia compared to those with normal uric acid.

Hyperuricemia: An Intriguing Connection to Metabolic Syndrome, Diabetes, Kidney Disease, and Hypertension

PURPOSE OF THE REVIEW

Our review explores the epidemiology, physiology, and clinical data surrounding the connection between hyperuricemia and metabolic syndrome, chronic kidney disease, and hypertension.

RECENT FINDINGS

Compelling physiologic mechanisms have been proposed to explain a causal relationship between hyperuricemia and metabolic syndrome, chronic kidney disease, and hypertension but clinical studies have given mixed results in terms of whether intervening with hyperuricemia using urate-lowering therapy has any beneficial effects for patients with these conditions. Despite the large amount of research already put into this topic, more randomized placebo-controlled trials are needed to more firmly establish whether a cause-effect relationship exists and whether lowering uric acid levels in patients with these conditions is beneficial.

Fractional Excretion of Urate is Positively Associated with Type 2 Diabetes in HUA Patients: A Cross-Sectional Study

Purpose

People with hyperuricemia (HUA) are often related to metabolic disorders such as diabetes, metabolic syndrome (MetS), and obesity. However, the correlation between excretion of uric acid and these diseases is unclear. Our study aimed to explore the relationship between uric acid excretion and type 2 diabetes (T2D).

Methods

A total of 228 HUA patients from Tianjin Medical University General Hospital from 2022 to 2023 were included in this study. We collected demographic, biochemical, and anthropometric data on each subject. Urine uric acid excretion (UUAE) was calculated enzymatically from a single urine collection that lasted 24 hours. And fractional excretion of uric acid (FEUA) was calculated from serum uric acid and creatinine and uric acid and creatinine. Binary logistic regression modeling assessed the association between uric acid excretion and T2D.

Results

Of the 228 subjects, 13.4% had T2D and 48.7% had obesity. The obesity group had a lower FEUA (p<0.05) and a higher UUAE compared to the control group (p<0.05). And FEUA had a stronger correlation with the risk of T2D (p<0.001). Also, there was a negative association between BMI and FEUA and a positive link between BMI and UUAE in the outpatients.

Conclusion

Increased FEUA levels were significantly associated with T2D in HUA patients. Therefore, routine calculating of FEUA is essential for proper diagnosis and appropriate treatment T2D of in HUA patients.

The agreement of low lean mass with obesity using different definitions and its correlation with hyperuricemia

Background

The agreement on the identification of sarcopenic obesity remains elusive, and its association with hyperuricemia remains unestablished. This study sought to evaluate the agreement of low lean mass (LLM) with obesity and its correlation with hyperuricemia.

Methods

A total of 25,252 study participants, comprising 4,597 individuals with hyperuricemia, were obtained from the National Health and Nutrition Examination Survey spanning the years 1999-2006 and 2011-2018. LLM with obesity was characterized by the coexistence of LLM, determined by the ratio of appendicular lean mass to body mass index (BMI), and three categories of obesity including BMI, body fat percentage (BF%), and waist circumference (WC). We employed Cohen's kappa to evaluate the agreement among the different diagnostic criteria and implemented survey multiple logistic regression and stratified analyses to explicate the connection between LLM with obesity and the risk of hyperuricemia.

Results

When defining obesity using BF%, BMI, and WC, the prevalence of LLM with obesity varied from 6.6 to 10.1%, with moderate-to-strong agreement. In the fully adjusted model, individuals with LLM or any of the three types of obesity exhibited notably elevated odds of developing hyperuricemia. Likewise, participants with LLM and obesity had 2.70 (LLM + BMI), 2.44 (LLM + BF%), and 3.12 (LLM + WC) times the risk of hyperuricemia, respectively, compared with healthy individuals. The association between LLM with obesity and hyperuricemia remained stable and significant across different age and sex subgroups.

Conclusion

When employing the three definitions of obesity, the incidence of LLM with obesity was not high, and the diagnostic agreement was relatively good. The participants with LLM and obesity exhibited an increased risk of hyperuricemia.

Relationship between serum uric acid in early pregnancy and gestational diabetes mellitus: a prospective cohort study

PURPOSE

The association between serum uric acid (UA) and gestational diabetes mellitus (GDM) was still unclear. Serum UA levels in pregnancy differed from that in non-pregnancy. This study aimed to investigate the changes of serum UA in early pregnancy, and to explore the association of serum UA with the risk of GDM.

METHODS

A prospective double-center study including 873 singleton pregnant women was conducted in Beijing, China since 2019 (clinical trial number: NCT03246295). Seventy-eight healthy non-pregnant women were selected to compare the changes of biomarkers in pregnancy. Spearman correlation and logistic regression analysis were performed to measure the relationship between serum UA in early pregnancy and GDM.

RESULTS

The incidence of GDM in our cohort was 20.27%(177/873). Compared with non-pregnant women, serum UA and creatinine decreased significantly during early pregnancy. Serum UA concentration in early pregnancy was significantly higher in GDM women than that in normal glucose tolerance (NGT) women [217.0(192.9, 272.0) μmol/l vs. 201.9(176.0, 232.0) μmol/l, p < 0.001]. After adjusted for confounding factors, elevated serum UA remained as an independent risk factor for GDM. The risk of GDM increased when serum UA was above 240 μmol/l (adjusted OR 1.964, 95% CI 1.296-2.977, p < 0.001), and stronger relationships between serum UA and GDM were observed in pregnant women aged over 35 years old and preBMI ≥ 24 kg/m2.

CONCLUSION

The normal range of serum UA and creatinine in pregnant women were lower than those in non-pregnant women. It is essential to monitor serum UA concentrations since early pregnancy to alert and prevent GDM, especially in older and heavier pregnant women.

CLINICAL TRIAL NUMBER

NCT03246295.

Exposure to Chinese famine and the risk of hyperuricemia in later life: a population-based cross-sectional study

Background

Limited studies have investigated the relationship between famine exposure and the risk of hyperuricemia in later life. Consequently, the primary purpose of the current study was to examine the potential association between exposure to Chinese famine and hyperuricemia, as well as any gender disparities in this relationship.

Method

The data were obtained from the China PEACE (China Patient-Centered Evaluative Assessment of Cardiac Events) Million Persons Project in Rongchang. The study participants were enrolled into different cohorts based on their birthdates: the fetal-exposed cohort (born between 1959 and 1962), the childhood-exposed cohort (born between 1949 and 1958), the adolescence-exposed cohort (born between 1941 and 1948), and the non-exposed cohorts (born between 1963 and 1974). The potential association between famine exposure and hyperuricemia was assessed using binary logistic regression models.

Results

A total of 6,916 individuals were enrolled in the current study with an average age of 60.11 ± 9.22 years, out of which 3,544 were women. After adjusting for confounding factors, fetal (OR = 0.530, 95% CI: 0.411-0.0.683), childhood (OR = 0.642, 95% CI: 0.494-0.833) exposure to the Chinese famine for men was negatively associated with hyperuricemia. Conversely, exposure to the Chinese famine during fetal (OR = 2.144, 95% CI: 1.622-2.834), childhood (OR = 1.485, 95% CI: 1.105-1.997), and adolescence (OR = 1.967, 95% CI: 1.465-2.641) for women was positively associated with hyperuricemia. Furthermore, the impact of famine on hyperuricemia that has been observed in exposed women might be intensified by the presence of dyslipidemia, abdominal obesity, and overweight/obesity.

Conclusion

Women exposed to the Chinese famine during fetal, childhood, and adolescence were positively associated with hyperuricemia, while men exhibited a negative association during fetal and childhood. Additionally, the effect of famine on hyperuricemia in exposed women appears to be intensified by the presence of dyslipidemia, abdominal obesity, and overweight/obesity.

Machine Learning Insights Into Uric Acid Elevation With Thiazide Therapy Commencement and Intensification

Background Elevated serum uric acid, associated with cardiovascular conditions such as atherosclerotic heart disease, hypertension, and heart failure, can be elevated by thiazide or thiazide-like drugs (THZ), essential in hypertension management. Identifying clinical determinants affecting THZ-related uric acid elevation is critical. Methods In this retrospective cross-sectional study, we explored the clinical determinants influencing uric acid elevation related to THZ, focusing on patients where THZ was initiated or the dose escalated. A cohort of 143 patients was analyzed, collecting baseline and control uric acid levels, alongside basic biochemical studies and clinical data. Feature selection was conducted utilizing criteria based on mean squared error increase and enhancement in node purity. Four machine learning algorithms - Random Forest, Neural Network, Support Vector Machine, and Gradient Boosting regressions - were applied to pinpoint clinical influencers. Results Significant features include uncontrolled diabetes, index estimated Glomerular Filtration Rate (eGFR) level, absence of insulin, action of indapamide, and absence of statin treatment, with absence of Sodium-glucose cotransporter 2 inhibitors (SGLT2i), low dose aspirin exposure, and older age also being noteworthy. Among the applied models, the Gradient Boosting regression model outperformed the others, exhibiting the lowest Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Squared Error (RMSE) values, and the highest R2 value (0.779). While Random Forest and Neural Network regression models were able to fit the data adequately, the Support Vector Machine demonstrated inferior metrics. Conclusions Machine learning algorithms are adept at accurately identifying the factors linked to uric acid fluctuations caused by THZ. This proficiency aids in customizing treatments more effectively, reducing the need to unnecessarily avoid THZ, and providing guidance on its use to prevent instances where uric acid levels could become problematic.

Uric Acid Levels, Number of Standard Modifiable Cardiovascular Risk Factors, and Prognosis in Patients With Coronary Artery Disease: A Large Cohort Study in Asia

Background Serum uric acid (UA) is correlated closely with traditional cardiovascular risk factors, which might interfere with the action of UA, in patients with coronary artery disease. We performed this study to evaluate the prognostic effect of UA levels in individuals with different numbers of standard modifiable cardiovascular risk factors (SMuRFs). Methods and Results In this prospective study, we consecutively enrolled 10 486 patients with coronary artery disease. They were stratified into 3 groups according to the tertiles of UA concentrations and, within each UA tertile, further classified into 3 groups by the number of SMuRFs (0-1 versus 2-3 versus 4). The primary end point was major adverse cardiovascular and cerebrovascular events (MACCEs), including death, myocardial infarction, stroke, and unplanned revascularization. Over a median follow-up of 2.4 years, 1233 (11.8%) MACCEs were recorded. Patients with high UA levels developed significantly higher risk of MACCEs than those with low UA levels. In addition, UA levels were positively associated with MACCEs as a continuous variable. More importantly, in patients with 0 to 1 SMuRF, the risks of MACCEs were significantly higher in the high-UA-level group (adjusted hazard ratio [HR], 1.469 [95% CI, 1.197-1.804]) and medium-UA-level group (adjusted HR, 1.478 [95% CI, 1.012-2.160]), compared with the low-UA-level group, whereas no significant association was found between UA levels and the risk of MACCEs in participants with 2 to 3 or 4 SMuRFs. Conclusions In patients with coronary artery disease who received evidence-based secondary prevention therapies, elevated UA levels might affect the prognosis of individuals with 0 to 1 SMuRF but not that of individuals with ≥2 SMuRFs.

The role of high fat diet on serum uric acid level among healthy male first degree relatives of type 2 diabetes mellitus

First-degree relatives (FDR) of type 2 diabetes mellitus have increased risk of developing insulin resistance-related disorders including hyperuricemia. We investigated metabolic profile and serum uric acid (SUA) metabolism in response to high-fat diet among healthy male FDR in comparison to those without family history of diabetes. A total of 30 FDR and 30 non-FDR subjects completed a 5-days-hypercaloric diet with fat added to regular daily intake. Despite similar insulin response, FDR displayed different changes in SUA compared to non-FDR subjects (0.26 ± 0.83 mg/dL vs - 0.21 ± 0.78 mg/dL, p = 0.028). In subgroup analyses stratified by body mass index and waist circumference, significant different SUA changes between FDR and non-FDR subjects were only found in obese (0.48 ± 0.87 mg/dL vs - 0.70 ± 0.71 mg/dL, p = 0.001) and centrally obese (0.59 ± 0.83 mg/dL vs - 0.55 ± 0.82 mg/dL, p = 0.011) subgroups. In multivariate analysis, visceral adiposity seemed mediating the different response in SUA metabolism between FDR and non-FDR subjects induced by short-term obesogenic diet.

Relationship between baseline and changed serum uric acid and the incidence of type 2 diabetes mellitus: a national cohort study

Objective

To explore the correlation between baseline serum uric acid (SUA) and SUA changes with the incidence of type 2 diabetes mellitus (T2DM) among middle-aged and older individuals.

Method

Binary logistic regression was used to calculate the odds ratio (ORs) and 95% confidence intervals (CIs) of the effects of baseline and changes in SUA on the incidence of T2DM. Stratified analysis was conducted based on sex, and the SUA levels were classified into four quartiles to assess the effect of baseline and relative changes in SUA on the incidence of T2DM. Furthermore, interaction analysis was performed between body mass index (BMI) and SUA, age and SUA, and sex and SUA.

Results

In the cohort study, the highest quartiles of SUA were significantly correlated with an increased incidence of T2DM among females in model 1 [OR = 2.231 (1.631, 3.050)], model 2 [OR = 2.090 (1.523, 2.867)], model 3 [OR = 2.075 (1.511, 2.849)], and model 4 [OR = 1.707 (1.234, 2.362)]. The highest quartiles of SUA had a statistically significant effect on the incidence of T2DM among all participants in model 1 [OR = 1.601 (1.277, 2.008)], model 2 [OR = 1.519 (1.204, 1.915)], model 3 [OR = 1.597 (1.257, 2.027)], and model 4 [OR = 1.380 (1.083, 1.760)]. Regarding the relative change of SUA, the highest quantiles of SUA were significantly correlated with an increased incidence of T2DM among females in model 1 [OR = 1.409 (1.050, 1.890)], model 2 [OR = 1.433 (1.067, 1.926)], and model 3 [OR = 1.420 (1.056, 1.910)], and there was a statistically significant correlation with incident T2DM among all participants in model 4 [OR = 1.346 (1.079, 1.680)] after adjusting for all covariates. However, there was no significant correlation between baseline, relative, and absolute changes in SUA and the incidence of T2DM among males. The interaction analysis demonstrated that sex, BMI, and the relative changes in SUA had a combined effect on the incidence of T2DM, while age and the changes in SUA had a joint effect on the incidence of T2DM only in females.

Conclusion

There was a positive association between SUA and the incidence of T2DM for all participants. However, significant sex differences in incidence were observed only in women, not men.

The effect of dietary approaches to stop hypertension and ketogenic diets intervention on serum uric acid concentration: a systematic review and meta-analysis of randomized controlled trials

Hyperuricemia as a risk factor for metabolic diseases is proved to be profoundly modified by dietary approaches. This systematic review and meta-analysis of randomized control trials (RCT) was conducted to investigate the effect of two nutritional interventions; dietary approaches to stop hypertension (DASH) diet and ketogenic diet (KD) on serum uric acid (UA) concentrations. Our systematic search was for RCTs in which KD or DASH diet were assigned to adults for at least 2 weeks or more. Until March 2023 in Embase, Web of Science, PubMed, and Scopus databases, 10 eligible RCTs that intervened with DASH diet (n = 4) or KD (n = 6) and had provided laboratory data on serum UA were found. Summary effect was calculated by random-effects model. Results from the meta-analysis of the 4 DASH diet RCTs with a total of 590 participants revealed significant decrease in serum UA after at least 4 weeks of interventions (mean difference (MD) = ‒0.25; 95% CI ‒0.4 to ‒0.1 mg/dL; p < 0.01; I² = 0%). The pooled meta-analysis of the 6 included RCTs of KD reporting data of 267 participants showed no significant changes in serum UA (MD = 0.26; 95% CI ‒0.47 to 0.98 mg/dL, I² = 95.32%). However, a non-significant reduction of UA in the subgroup analysis of very low-calorie KD (VLCKD) studies (MD = ‒0.04; 95% CI ‒0.29 to 0.22, I² = 0%) was obtained. DASH diet has an ameliorating effect on serum UA and may be recommended for hyperuricemia states such as gout. In addition, we have shown that serum UA level following KD remained unchanged. Although, in view of the heterogeneity across the studies, further investigations are needed to determine the effect of KD and VLKD on serum UA concentrations.

Genetic and Physiological Effects of Insulin-Like Growth Factor-1 (IGF-1) on Human Urate Homeostasis

SIGNIFICANCE STATEMENT

Hyperinsulinemia induces hyperuricemia by activating net renal urate reabsorption in the renal proximal tubule. The basolateral reabsorptive urate transporter GLUT9a appears to be the dominant target for insulin. By contrast, IGF-1 infusion reduces serum urate (SU), through mechanisms unknown. Genetic variants of IGF1R associated with reduced SU have increased IGF-1R expression and interact with genes encoding the GLUT9 and ABCG2 urate transporters, in a sex-specific fashion, which controls the SU level. Activation of IGF-1/IGF-1R signaling in Xenopus oocytes modestly activates GLUT9a and inhibits insulin's stimulatory effect on the transporter, which also activates multiple secretory urate transporters-ABCG2, ABCC4, OAT1, and OAT3. The results collectively suggest that IGF-1 reduces SU by activating secretory urate transporters and inhibiting insulin's action on GLUT9a.

BACKGROUND

Metabolic syndrome and hyperinsulinemia are associated with hyperuricemia. Insulin infusion in healthy volunteers elevates serum urate (SU) by activating net urate reabsorption in the renal proximal tubule, whereas IGF-1 infusion reduces SU by mechanisms unknown. Variation within the IGF1R gene also affects SU levels.

METHODS

Colocalization analyses of a SU genome-wide association studies signal at IGF1R and expression quantitative trait loci signals in cis using COLOC2, RT-PCR, Western blotting, and urate transport assays in transfected HEK 293T cells and in Xenopus laevis oocytes.

RESULTS

Genetic association at IGF1R with SU is stronger in women and is mediated by control of IGF1R expression. Inheritance of the urate-lowering homozygous genotype at the SLC2A9 locus is associated with a differential effect of IGF1R genotype between men and women. IGF-1, through IGF-1R, stimulated urate uptake in human renal proximal tubule epithelial cells and transfected HEK 293T cells, through activation of IRS1, PI3/Akt, MEK/ERK, and p38 MAPK; urate uptake was inhibited in the presence of uricosuric drugs, specific inhibitors of protein tyrosine kinase, PI3 kinase (PI3K), ERK, and p38 MAPK. In X. laevis oocytes expressing ten individual urate transporters, IGF-1 through endogenous IGF-1R stimulated urate transport mediated by GLUT9, OAT1, OAT3, ABCG2, and ABCC4 and inhibited insulin's stimulatory action on GLUT9a and OAT3. IGF-1 significantly activated Akt and ERK. Specific inhibitors of PI3K, ERK, and PKC significantly affected IGF-1 stimulation of urate transport in oocytes.

CONCLUSIONS

The combined results of infusion, genetics, and transport experiments suggest that IGF-1 reduces SU by activating urate secretory transporters and inhibiting insulin's action.

Association between serum uric acid levels and atrial fibrillation in different fasting glucose patterns: A case-control study

BACKGROUND

Previous studies have shown both dysglycaemia and hyperuricemia are associated with an increased risk of atrial fibrillation (AF), while the relationship between serum uric acid (SUA) levels and AF in different fasting glucose patterns (FBG) is unclear. Therefore, this study aimed to determine the association between SUA and AF in different FBG patterns.

METHODS

A total of 1840 patients in this case-control study were enrolled, including 920 AF patients and 920 controls. Patients were divided into three groups according to the different FBG patterns: normoglycemic, impaired fasting glucose (IFG), and diabetes mellitus (DM). Multivariate logistic regression models were performed to evaluate the relationship between SUA and AF in different FBG patterns. Pearson correlation analysis was used to explore the correlation between SUA and metabolic factors. Receiver operating characteristic (ROC) curve models indicated the diagnostic efficiency of SUA for diagnosing AF.

RESULTS

SUA was independently associated with AF after adjusting for all confounding factors in different FBG patterns(normoglycemic: OR=1.313, 95% CI:1.120-1.539; IFG: OR=1.386, 95% CI:1.011-1.898; DM: OR=1.505, 95% CI:1.150-1.970). Pearson's correlation analysis suggested that SUA in AF patients was correlated with several different metabolic factors in different FBG patterns (p<0.05). ROC curve analysis showed that SUA in the normoglycemic group combined with CHD and APOB [AUC: 0.906 (95% CI: 0.888-0.923)], in the IFG group combined with CHD and Scr [AUC: 0.863 (95% CI: 0.820-0.907)], in the DM group combined with CHD and SBP [AUC: 0.858 (95% CI: 0.818-0.898)] had the highest AUC for predicting AF.

CONCLUSION

Findings implied a significant association between SUA and AF in different FBG patterns and provide specific models combined with other factors (CHD, APOB, SCr, SBP), which might contribute to the diagnosis of AF.

Sex-dependent association analysis between serum uric acid and spontaneous hemorrhagic transformation in patients with ischemic stroke

Objective

The association between serum uric acid (UA) and spontaneous hemorrhagic transformation (HT) has been seldom studied, and the role of UA in spontaneous HT remains unclear. This study aims to investigate the sex-dependent association between UA and spontaneous HT in patients with ischemic stroke.

Method

We retrospectively included patients with ischemic stroke in a tertiary academic hospital between December 2016 and May 2020. Patients were included if they presented within 24 h after the onset of symptoms and did not receive reperfusion therapy. Spontaneous HT was determined by an independent evaluation of neuroimaging by three trained neurologists who were blinded to clinical data. A univariate analysis was performed to identify factors related to spontaneous HT. Four logistic regression models were established to adjust each factor and assess the association between UA and spontaneous HT.

Results

A total of 769 patients were enrolled (64.6% were male patients and 3.9% had HT). After adjusting the confounders with a P < 0.05 (model A) in the univariate analysis, the ratio of UA and its interquartile range (RUI) was independently associated with spontaneous HT in male patients (OR: 1.85; 95% CI: 1.07-3.19; P = 0.028), but not in female patients (OR: 1.39; 95% CI: 0.28-6.82; P = 0.685). In models B-D, the results remain consistent with model A after the adjustment for other potential confounders.

Conclusions

Higher serum UA was independently associated with a higher occurrence of spontaneous HT in male patients who were admitted within 24 h after the stroke onset without receiving reperfusion therapy.

Urinalysis of individuals with renal hyperfiltration using ATR-FTIR spectroscopy

Abnormal increased glomerular filtration rate (GFR), otherwise known as renal hyperfiltration (RHf), is associated with an increased risk of chronic kidney disease and cardiovascular mortality. Although it is not considered as a disease alone in medicine today, early detection of RHf is essential to reducing risk in a timely manner. However, detecting RHf is a challenge since it does not have a practical biochemical marker that can be followed or quantified. In this study, we tested the ability of ATR-FTIR spectroscopy to distinguish 17 individuals with RHf (hyperfiltraters; RHf (+)), from 20 who have normal GFR (normofiltraters; RHf(-)), using urine samples. Spectra collected from hyperfiltraters were significantly different from the control group at positions 1621, 1390, 1346, 933 and 783/cm. Intensity changes at these positions could be followed directly from the absorbance spectra without the need for pre-processing. They were tentatively attributed to urea, citrate, creatinine, phosphate groups, and uric acid, respectively. Using principal component analysis (PCA), major peaks of the second derivative forms for the classification of two groups were determined. Peaks at 1540, 1492, 1390, 1200, 1000 and 840/cm were significantly different between the two groups. Statistical analysis showed that the spectra of normofiltraters are similar; however, those of hyperfiltraters show diversity at multiple positions that can be observed both from the absorbance spectra and the second derivative profiles. This observation implies that RHf can simultaneously affect the excretion of many substances, and that a spectroscopic analysis of urine can be used as a rapid and non-invasive pre-screening tool.

Association of Serum Uric Acid with Diabetes in Premenopausal and Postmenopausal Women-A Prospective Cohort Study in Shanghai, China

There have been few prospective studies on the association between serum uric acid (SUA) and the risk of diabetes in women, and there have been few large-scale Chinese studies based on menopause to investigate the association. Therefore, the present study aimed to investigate the above relationship in Chinese female adults without diabetes. Methods: Data from 5743 premenopausal women and 11,287 postmenopausal women aged 20−74 years were obtained from the Shanghai Suburban Adult Cohort and Biobank (SSACB) study conducted in China. Cox regression models were applied to evaluate the association between SUA levels and the risk of diabetes. Restricted cubic spline analysis and stratified analysis on the basis of menopausal status were performed to explore the dose−response association between SUA levels and diabetes. Results: Among 17,030 participants, incidence rates of diabetes were 3.44/1000 person-years in premenopausal and 8.90/1000 person-years in postmenopausal women. The SUA levels in postmenopausal women were higher than that in premenopausal women (p < 0.0001). In Cox regression analysis, after adjusting for confounding factors, for each 10 µmol/L increase in SUA levels, the adjusted HR of diabetes was 1.01 (95% CI: 0.97−1.04) in postmenopausal women, and 1.03 (95% CI: 1.01−1.04) in premenopausal women. Compared with the lowest quartile of SUA levels, the HR (95% CI) of diabetes in the highest quartile was 0.99 (0.55−1.79) in premenopausal women and 1.39 (1.07−1.81) in postmenopausal women. Compared with those without hyperuricemia, the HR (95% CI) for diabetes was 1.89 (0.67−5.31) in premenopausal women with hyperuricemia, and 1.55 (1.19−2.02) in postmenopausal women. Moreover, restricted cubic splines models showed that there was a linear relationship between SUA levels and diabetes risk in premenopausal (p for nonlinear = 0.99) and postmenopausal women (p for nonlinear = 0.95). Furthermore, the restricted cubic spline graph showed that the risk of diabetes in postmenopausal women increased with an increase in SUA levels (p = 0.002). Conclusions: In a cohort of Chinese adult women, SUA levels are associated with diabetes risk in postmenopausal women, but this association was not observed in premenopausal women.

New insight into the management of renal excretion and hyperuricemia: Potential therapeutic strategies with natural bioactive compounds

Hyperuricemia is the result of increased production and/or underexcretion of uric acid. Hyperuricemia has been epidemiologically associated with multiple comorbidities, including metabolic syndrome, gout with long-term systemic inflammation, chronic kidney disease, urolithiasis, cardiovascular disease, hypertension, rheumatoid arthritis, dyslipidemia, diabetes/insulin resistance and increased oxidative stress. Dysregulation of xanthine oxidoreductase (XOD), the enzyme that catalyzes uric acid biosynthesis primarily in the liver, and urate transporters that reabsorb urate in the renal proximal tubules (URAT1, GLUT9, OAT4 and OAT10) and secrete urate (ABCG2, OAT1, OAT3, NPT1, and NPT4) in the renal tubules and intestine, is a major cause of hyperuricemia, along with variations in the genes encoding these proteins. The first-line therapeutic drugs used to lower serum uric acid levels include XOD inhibitors that limit uric acid biosynthesis and uricosurics that decrease urate reabsorption in the renal proximal tubules and increase urate excretion into the urine and intestine via urate transporters. However, long-term use of high doses of these drugs induces acute kidney disease, chronic kidney disease and liver toxicity. Therefore, there is an urgent need for new nephroprotective drugs with improved safety profiles and tolerance. The current systematic review summarizes the characteristics of major urate transporters, the mechanisms underlying the pathogenesis of hyperuricemia, and the regulation of uric acid biosynthesis and transport. Most importantly, this review highlights the potential mechanisms of action of some naturally occurring bioactive compounds with antihyperuricemic and nephroprotective potential isolated from various medicinal plants.

Increased risk of incident gout in young men with metabolic syndrome: A nationwide population-based cohort study of 3.5 million men

Background

To date, few studies have focused on risk factors for gout in young people, and large-scale studies on the relationship between metabolic syndrome (MetS) and gout are lacking. We aimed to investigate the association between gout and MetS in a large nationwide population-based cohort of young men who participated in national health examination.

Materials and methods

Cohort included men aged 20–39 years who participated in a health check-up in 2009–2012. A total of 3,569,104 subjects was included in the study, excluding those who had a previous diagnosis of gout or had renal impairment. The outcome was the occurrence of gout, which was defined using the diagnosis code of gout in the claims database. Cox proportional hazard model was used to evaluate the association between MetS and incident gout.

Results

Mean follow-up duration was 7.35 ± 1.24 years and the incidence rate of gout was 3.36 per 1,000 person-years. The risk of gout in subjects with MetS was 2.4-fold higher than subjects without MetS. Among the components of MetS, hypertriglyceridemia and abdominal obesity showed the greatest association with gout. As the number of MetS components increased, the risk of gout increased. The association between gout and MetS was more pronounced in relatively young subjects and in low- or normal-weight subjects.

Conclusion

Metabolic syndrome is an important risk factor for the gout in young men. In particular, the association between MetS and gout was greater in young and non-obese men. Management of MetS in young men will be important for future gout prevention.

Trends in the Contribution of Genetic Susceptibility Loci to Hyperuricemia and Gout and Associated Novel Mechanisms

Hyperuricemia and gout are complex diseases mediated by genetic, epigenetic, and environmental exposure interactions. The incidence and medical burden of gout, an inflammatory arthritis caused by hyperuricemia, increase every year, significantly increasing the disease burden. Genetic factors play an essential role in the development of hyperuricemia and gout. Currently, the search on disease-associated genetic variants through large-scale genome-wide scans has primarily improved our understanding of this disease. However, most genome-wide association studies (GWASs) still focus on the basic level, whereas the biological mechanisms underlying the association between genetic variants and the disease are still far from well understood. Therefore, we summarized the latest hyperuricemia- and gout-associated genetic loci identified in the Global Biobank Meta-analysis Initiative (GBMI) and elucidated the comprehensive potential molecular mechanisms underlying the effects of these gene variants in hyperuricemia and gout based on genetic perspectives, in terms of mechanisms affecting uric acid excretion and reabsorption, lipid metabolism, glucose metabolism, and nod-like receptor pyrin domain 3 (NLRP3) inflammasome and inflammatory pathways. Finally, we summarized the potential effect of genetic variants on disease prognosis and drug efficacy. In conclusion, we expect that this summary will increase our understanding of the pathogenesis of hyperuricemia and gout, provide a theoretical basis for the innovative development of new clinical treatment options, and enhance the capabilities of precision medicine for hyperuricemia and gout treatment.

The effect of Glucagon-like peptide-1 receptor agonists on serum uric acid concentration: A systematic review and meta-analysis

AIMS

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a class of medications mainly used for the treatment of type 2 diabetes. They improve glucose tolerance, increase insulin secretion, and induce weight loss. There is controversy about the effect of GLP-1RAs on serum uric acid (SUA) concentration. Our systematic review aims to objectively answer whether GLP-1RAs affect SUA levels.

METHODS

We performed a systematic search on PubMed, Web of Science, Embase, Scopus, and Google Scholar datasets up to 27August,2021 with a language restriction of English only. Randomized controlled trials, observational studies, uncontrolled trials, and conference abstracts were included. Studies with insufficient data, irrelevant types of study, and follow-up duration of less than a month were excluded from the review. After critical appraisal by the Joanna Briggs Institute checklists, articles underwent data extraction using a pre-specified Microsoft Excel sheet.

RESULTS

Of 1004 identified studies, 17 were eligible for inclusion in this systematic review. Pre- to post-administration analysis of GLP-1RA effects on SUA demonstrated that GLP-1RAs could significantly reduce SUA concentration (difference in means=-0.341;SE=0.063;P-value<0.001). However, when compared to placebo, GLP-1 RAs did not perform any better in lowering SUA concentration (difference in means=-0.455;SE=0.259;P-value=0.079). Surprisingly, the active controls, that included insulin, metformin, sodium-glucose co-transporter 2 (SGLT-2) inhibitors, and dipeptidyl-peptidase 4 (DPP-4) inhibitors, did outperform GLP-1RAs in reducing SUA concentration (difference in means=0.250;SE=0.038;P-value<0.001).

CONCLUSIONS

Administration of GLP-1RAs can result in a significant reduction in SUA concentration. However, this reduction is less than that seen with the use of insulin, metformin, and SGLT-2 inhibitors.

Association between glucokinase regulator gene polymorphisms and serum uric acid levels in Taiwanese adolescents

The glucokinase regulator gene (GCKR) is located on chromosome 2p23. It plays a crucial role in maintaining plasma glucose homeostasis and metabolic traits. Recently, genome-wide association studies have revealed a positive association between hyperuricemia and GCKR variants in adults. This study investigated this genetic association in Taiwanese adolescents. Data were collected from our previous cross-sectional study (Taipei Children Heart Study). The frequencies of various genotypes (CC, CT, and TT) or alleles (C and T) of the GCKR intronic single-nucleotide polymorphism (SNP) rs780094 and the coding SNP rs1260326 (Pro446Leu, a common 1403C-T transition) were compared between a total of 968 Taiwanese adolescents (473 boys, 495 girls) with hyperuricemia or normal uric acid levels on the basis of gender differences. Logistic and linear regression analyses explored the role of GCKR in abnormal uric acid (UA) levels. Boys had higher UA levels than girls (6.68 ± 1.29 and 5.23 ± 0.95 mg/dl, respectively, p < 0.001). The analysis of both SNPs in girls revealed that the T allele was more likely to appear in patients with hyperuricemia than the C allele. After adjusting for confounders, the odds ratio (OR) for hyperuricemia incidence in the TT genotype was 1.75 (95% confidence interval [CI] 1.02–3.00), which was higher than that in the C allele carriers in rs1260326 in the girl population. Similarly, the TT genotypes had a higher risk of hyperuricemia, with an OR of 2.29 (95% CI 1.11–4.73) for rs1260326 and 2.28 (95% CI 1.09–4.75) for rs780094, than the CC genotype in girl adolescents. The T (Leu446) allele of GCKR rs1260326 polymorphism is associated with higher UA levels in Taiwanese adolescent girls.

Uric Acid and Oxidative Stress-Relationship with Cardiovascular, Metabolic, and Renal Impairment

Background: The connection between uric acid (UA) and renal impairment is well known due to the urate capacity to precipitate within the tubules or extra-renal system. Emerging studies allege a new hypothesis concerning UA and renal impairment involving a pro-inflammatory status, endothelial dysfunction, and excessive activation of renin–angiotensin–aldosterone system (RAAS). Additionally, hyperuricemia associated with oxidative stress is incriminated in DNA damage, oxidations, inflammatory cytokine production, and even cell apoptosis. There is also increasing evidence regarding the association of hyperuricemia with chronic kidney disease (CKD), cardiovascular disease, and metabolic syndrome or diabetes mellitus. Conclusions: Important aspects need to be clarified regarding hyperuricemia predisposition to oxidative stress and its effects in order to initiate the proper treatment to determine the optimal maintenance of UA level, improving patients’ long-term prognosis and their quality of life.

Hypouricemia and Urate Transporters

Hypouricemia is recognized as a rare disorder, defined as a serum uric acid level of 2.0 mg/dL or less. Hypouricemia is divided into an overexcretion type and an underproduction type. The former typical disease is xanthinuria, and the latter is renal hypouricemia (RHUC). The frequency of nephrogenic hypouricemia due to a deficiency of URAT1 is high in Japan, accounting for most asymptomatic and persistent cases of hypouricemia. RHUC results in a high risk of exercise-induced acute kidney injury and urolithiasis. It is vital to promote research on RHUC, as this will lead not only to the elucidation of its pathophysiology but also to the development of new treatments for gout and hyperuricemia.

Factors Influencing Change in Serum Uric Acid After Administration of the Sodium-Glucose Cotransporter 2 Inhibitor Luseogliflozin in Patients With Type 2 Diabetes Mellitus

Although sodium-glucose cotransporter 2 (SGLT2) inhibitors lower serum uric acid, their long-term effect on uric acid metabolism is not well understood. We analyzed pooled data from studies wherein patients with type 2 diabetes mellitus received luseogliflozin, an SGLT2 inhibitor. Upon stratifying patients by baseline glycated hemoglobin (HbA1c ) or serum uric acid, lower HbA1c or higher serum uric acid level was associated with a greater reduction in serum uric acid after treatment. At week 12 of treatment, significant increases in urinary glucose/creatinine (Cr) ratio and urinary uric acid clearance/Cr clearance ratio (CUA /CCr ratio) and a significant reduction in serum uric acid were observed. Comparison of the subgroups of patients with a reduction or an increase in serum uric acid showed that the increase subgroup had a higher estimated glomerular filtration rate (eGFR) at baseline, and the eGFR was significantly reduced, associated with a significant reduction in the CUA /CCr ratio. Multiple regression analysis showed that the reduction in serum uric acid in the luseogliflozin group was strongly associated with baseline high serum uric acid, low HbA1c levels, and an increase in eGFR. Luseogliflozin was shown to reduce serum uric acid by enhancing urinary uric acid excretion in association with increased urinary glucose. Treatment with luseogliflozin resulted in increased serum uric acid in some patients, which may be due to reduced glomerular filtration of uric acid via the tubuloglomerular feedback. SGLT2 inhibitors reduced serum uric acid desirably in patients with type 2 diabetes mellitus with low HbA1c and high serum uric acid.

The Relation of Accelerometer-Measured Physical Activity and Serum Uric Acid Using the National Health and Nutrition Survey (NHANES) 2003–2004

Objective: Gout is a crystal-induced inflammatory arthritis caused by elevated uric acid. Physical activity has the potential to reduce serum uric acid (SUA), thus improving the disease burden of gout. In this study, we examined the association of objectively-measured physical activity and SUA.

Methods: A cross-sectional study was conducted using survey, laboratory, and accelerometer data from the 2003–2004 National Health and Nutrition Examination Survey (NHANES). SUA concentrations (mg/dL) were obtained during an initial exam, and then physical activity (kCal/day) was measured with 7 days of ActiGraph accelerometry in participants (n = 3,475) representative of the ambulatory, non-institutionalized US civilian population. Regression, including restricted cubic splines, was used to assess the relation of physical activity and SUA in bivariate and adjusted models. Covariates included age, gender, race/ethnicity, alcohol use, body mass index, renal function, and urate-lowering therapy.

Results: In the bivariate model, physical activity was correlated with SUA concentrations and included a non-linear component (p < 0.01). In the adjusted model, linear splines were employed with a node at the SUA nadir of 5.37mg/dL; this occurred at 703 kCal/day of physical activity. The association of physical activity and SUA was negative from 0 to 703 kCal/day (p = 0.07) and positive >703 kCal/day (p < 0.01 for the change in slope).

Conclusion: Physical activity and SUA are associated in a non-linear fashion, with a minimum estimated SUA at 703 kCal/day of objectively-measured physical activity. These findings raise intriguing questions about the use of physical activity as a potential adjunctive therapy in patients with gout, and further interventional studies are needed to elucidate the effects of moderate intensity exercise on SUA concentrations.

Adipose Tissue Insulin Resistance Is Positively Associated With Serum Uric Acid Levels and Hyperuricemia in Northern Chinese Adults

OBJECTIVE

Adipose tissue plays a crucial role in serum uric acid (UA) metabolism, but the relative contribution of adipose tissue insulin resistance (IR) to serum UA levels and hyperuricemia have not explicitly been illustrated. Herein, we aimed to investigate the association between the adipose tissue insulin resistance index (Adipo-IR) and hyperuricemia in this cross-sectional study. The homeostasis model assessment of insulin resistance (HOMA-IR) index, another widely applied marker to determine systemic IR, was also explored.

METHODS

A total of 5821 adults were included in this study. The relationship between Adipo-IR or HOMA-IR and serum UA levels was assessed by multivariate linear regression. Binary logistic regression analyses were applied to determine the sex-specific association of the Adipo-IR tertiles and HOMA-IR tertiles with hyperuricemia. Participants were then divided into normal BMI (18.5 ≤ BMI < 24) and elevated BMI (BMI ≥ 24) groups for further analysis.

RESULTS

Both Adipo-IR and HOMA-IR were positively correlated with serum UA (P < 0.001). Compared with the lowest tertile, the risks of hyperuricemia increased across Adipo-IR tertiles (middle tertile: OR 1.52, 95%CI 1.24-1.88; highest tertile: OR 2.10, 95%CI 1.67-2.63) in men after full adjustment (P for trend < 0.001). In women, only the highest tertile (OR 2.09, 95%CI 1.52-2.87) was significantly associated with hyperuricemia. Those associations remained significant in participants with normal BMI status. As for HOMA-IR, only the highest tertile showed positive relationships with hyperuricemia in both genders after full adjustment (P for trend < 0.001). The association between HOMA-IR and hyperuricemia disappeared in men with normal BMI status.

CONCLUSIONS

Adipo-IR was strongly associated with serum UA and hyperuricemia regardless of BMI classification. In men with normal BMI, Adipo-IR, rather than HOMA-IR, was closely associated with hyperuricemia. Altogether, our finding highlights a critical role of adipose tissue IR on serum UA metabolism and hyperuricemia.

Uric Acid Variability as a Predictive Marker of Newly Developed Cardiovascular Events in Type 2 Diabetes

Background: Cardiovascular disease (CVD) is associated with morbidity and mortality in patients with type 2 diabetes mellitus (T2D). However, the role of serum uric acid as a risk factor for developing cardiovascular disease is controversial. This study investigated whether uric acid variability was associated with new-onset symptomatic CVD in patients with T2D, requiring percutaneous coronary intervention. Methods: A total of 1,071 patients were enrolled in this retrospective cross-sectional study after propensity score matching. Patients with T2D and new-onset symptomatic CVD who received percutaneous coronary intervention for the first time, and with at least three consecutive 6-monthly measurements of serum uric acid were recruited from Severance Hospital between January 2015 and December 2019. Uric acid variability was measured by average successive variability (ASV) and analyzed to evaluate a possible correlation with the risk of developing CVD. Results: The patients were divided into quartiles based on the uric acid variability. Patients in the highest quartile were older and presented lower renal function and a higher mortality from CVD. There was a linear association between a high uric acid variability and the development of CVD. Compared to the lowest quartile, patients in the higher quartiles had a higher risk of CVD [quartile 3: adjusted odds ratio (aOR) = 1.76; 95% confidence interval (CI), 1.20-2.82; P = 0.019; quartile 4 aOR = 2.89; 95% CI, 1.74-4.80; P < 0.001]. Conclusion: High uric acid variability is independently associated with an increased risk of new-onset symptomatic CVD requiring percutaneous coronary intervention in patients with T2D. Thus, maintaining serum uric acid in a narrow range by prescribing effective medications is essential to prevent new-onset CVD in patients with T2D. Nonetheless, the potential use of uric acid variability as a predictive marker of CVD in patients with T2D needs further validation.

Metabolic Syndrome-Related Hyperuricemia is Associated with a Poorer Prognosis in Patients with Colorectal Cancer: A Multicenter Retrospective Study

PURPOSE

Hyperuricemia and metabolic syndrome (MetS) have been shown to correlate with prognosis in patients with malignant tumors. The present study evaluated the relationship between preoperative hyperuricemia and MetS in colorectal cancer (CRC) patients and analyzed the effect of this combination on prognosis within 5 years.

PATIENTS AND METHODS

The study enrolled patients who had undergone radical CRC resection at three independent medical centers from January 2014 to December 2016. Patients were preoperatively categorized into four groups, those with hyperuricemia alone (H), those with MetS alone (MS), those with MetS-related hyperuricemia (MSH), and those with neither condition (control [C] group). The disease-free survival (DFS) and overall survival (OS) rates of these four groups were compared.

RESULTS

The study population consisted of 1271 patients, with 114, 201, 101, and 855 patients categorized into the H, MS, MSH and C groups, respectively. Preoperative MetS was found to be significantly associated with hyperuricemia (P < 0.001). Multivariate Cox regression analysis showed that MetS-related hyperuricemia (hazard ratio [HR] = 2.728; P < 0.001) and MetS alone (HR = 1.631; P < 0.001) were independent predictors of death, whereas simple hyperuricemia was not (P > 0.1). Relative to the C group, the MSH group had the highest rate of tumor recurrence or metastasis (HR = 5.103, P < 0.001), followed by the MS (HR = 2.231, P < 0.001) group. In contrast, prognosis did not differ significantly in the H and C groups (P > 0.1). MetS was significantly associated with poor prognosis, with MetS-related hyperuricemia resulting in a significantly poorer prognosis. In contrast, hyperuricemia alone had no effect on the long-term prognosis of CRC patients.

CONCLUSION

This study highlights the prognostic importance of MetS-related hyperuricemia on the survival of patients with CRC.

Prediction model for the onset risk of impaired fasting glucose: a 10-year longitudinal retrospective cohort health check-up study

BACKGROUND

Impaired fasting glucose (IFG) is a prediabetic condition. Considering that the clinical symptoms of IFG are inconspicuous, these tend to be easily ignored by individuals, leading to conversion to diabetes mellitus (DM). In this study, we established a prediction model for the onset risk of IFG in the Chongqing health check-up population to provide a reference for prevention in a health check-up cohort.

METHODS

We conducted a retrospective longitudinal cohort study in Chongqing, China from January 2009 to December 2019. The qualified subjects were more than 20 years old and had more than two health check-ups. After following the inclusion and exclusion criteria, the cohort population was randomly divided into a training set and a test set at a ratio of 7:3. We first selected the predictor variables through the univariate generalized estimation equation (GEE), and then the training set was used to establish the IFG risk model based on multivariate GEE. Finally, the sensitivity, specificity, and receiver operating characteristic curves were used to verify the performance of the model.

RESULTS

A total of 4,926 subjects were included in this study, with an average of 3.87 check-up records, including 2,634 males and 2,292 females. There were 442 IFG cases during the follow-up period, including 286 men and 156 women. The incidence density was 26.88/1000 person-years for men and 18.53/1000 person-years for women (P<0.001). The predictor variables of our prediction model include male (relative risk (RR) =1.422, 95 % confidence interval (CI): 0.923-2.193, P=0.3849), age (RR=1.030, 95 %CI: 1.016-1.044, P<0.0001), waist circumference (RR=1.005, 95 %CI: 0.999-1.012, P=0.0975), systolic blood pressure (RR=1.004, 95 %CI: 0.993-1.016, P=0.4712), diastolic blood pressure (RR=1.023, 95 %CI: 1.005-1.041, P=0.0106), obesity (RR=1.797, 95 %CI: 1.126-2.867, P=0.0140), triglycerides (RR=1.107, 95 %CI: 0.943-1.299, P=0.2127), high-density lipoprotein cholesterol (RR=0.992, 95 %CI: 0.476-2.063, P=0.9818), low-density lipoprotein cholesterol (RR=1.793, 95 %CI: 1.085-2.963, P=0.0228), blood urea (RR=1.142, 95 %CI: 1.022-1.276, P=0.0192), serum uric acid (RR=1.004, 95 %CI: 1.002-1.005, P=0.0003), total cholesterol (RR=0.674, 95 %CI: 0.403-1.128, P=0.1331), and serum creatinine levels (RR=0.960, 95 %CI: 0.945-0.976, P<0.0001). The area under the receiver operating characteristic curve (AUC) in the training set was 0.740 (95 %CI: 0.712-0.768), and the AUC in the test set was 0.751 (95 %CI: 0.714-0.817).

CONCLUSIONS

The prediction model for the onset risk of IFG had good predictive ability in the health check-up cohort.

Assessment of the relationship between serum uric acid levels and liver enzymes activity in Bangladeshi adults

Serum uric acid (SUA) level has been suggested to be associated with cardiovascular disease, diabetes and metabolic syndrome. However, little is known about the relationship between SUA and liver enzymes activity in the general population. The present study aimed to assess the relationship between SUA and serum liver enzymes in an adult population in Bangladesh. In this cross-sectional study, a total of 410 blood samples were collected from apparently healthy adults aged > 18 years. SUA, liver enzymes, lipid profile and other biochemical markers were measured in the collected samples by using standard methods. Multinomial logistic regression model was used to assess the relationship between SUA and elevated levels of liver enzymes among the participants. Overall, the prevalence of hyperuricemia was 30.1% with 32.2% in male and 18.6% in female participants. About 33% of the participants had at least one or more elevated levels of liver enzymes. The mean level of SUA was significantly higher in males (389.3 ± 96.9 µmol/L) than in the female (290.4 ± 89.8 µmol/L) subjects (p < 0.001). There was a significant difference in the mean levels of serum ALT and GGT between the male (34.5 ± 16.0 U/L and 26.7 ± 19.5 U/L, respectively) and female (25.0 ± 13.0 U/L and 19.5 ± 13.2 U/L, respectively) participants (p < 0.001 and p < 0.01, respectively). An increasing trend was observed in the mean levels of serum ALT and GGT across the SUA quartile groups (p < 0.001 and p < 0.01, respectively). SUA showed a positive and significant correlation with serum ALT (p < 0.001) and GGT (p < 0.01). In further statistical analysis after adjustment for potential confounders, SUA showed an independent and significant association with serum ALT and GGT in all regression models. In conclusion, SUA was strongly associated with serum levels of ALT and GGT after adjustment for potential confounders. More prospective studies are needed to clarify the complex relationship between SUA and liver enzymes in the general population.

Association of ABCG2 rs2231142 Allele and BMI With Hyperuricemia in an East Asian Population

Objectives: Genetic variants and obesity are risk factors for hyperuricemia (HUA). Recent genome-wide association studies have identified ABCG2 rs2231142 as one of the most prominent genetic variants for HUA in an East Asian population. Nevertheless, no large-scale studies have demonstrated any interactive effects between this variant and obesity on serum urate level in Asians. This study aimed to determine the interaction of ABCG2 rs2231142 variant and body mass index (BMI) and its effect on risk of HUA in an East Asian population.

Methods: The study was conducted using the Taiwan Biobank database, a population-based biomedical research database of patients with Taiwanese Han Chinese ancestry aged 30–70years between September 2014 and May 2017. Detailed physical information on participants were collected by questionnaires and genotyping using Affymetrix TWB 650K SNP chip. The primary outcome was HUA, defined as a serum uric acid level>7.0mg/dl. Odds ratio (OR) of HUA was analyzed using logistic regression models and the effects of interaction between ABCG2 rs2231142 variants and BMI on serum uric acid level were explored.

Results: We identified 25,245 subjects, 4,228 (16.75%) of whom had HUA. The prevalence of HUA was 30% in men and 3.8% in women. The risk of HUA was significantly associated with ABCG2 rs2231142 risk T allele, with more HUA in TT genotype (OR: 2.40, 95% CI: 2.11–2.72, p<0.001) and TG genotype (OR: 1.64, 95% CI: 1.51–1.78, p<0.001) in men, and TT genotype (OR: 2.42, 95% CI: 1.83–3.20, p<0.001) and TG genotype (OR: 1.82, 95% CI: 1.46–2.23, p<0.001) in women, compared with their counterparts. Moreover, we found a strong genetic-environmental interaction associated with the risk of HUA. There was increased risk of HUA by the interaction of ABCG2 rs2231142 variant and BMI for TT genotype (OR: 7.42, 95% CI: 2.54–21.7, p<0.001) and TG genotype (OR: 4.25, 95% CI: 2.13–8.47, p<0.001) in men compared with the GG genotype in men, and for TT genotype (OR: 25.43, 95% CI: 3.75–172.41, p<0.001) and TG genotype (OR: 3.05, 95% CI: 0.79–11.71, p=0.011) in women compared with the GG genotype in women.

Conclusion: The risk of HUA was markedly increased by the interaction of ABCG2 rs2231142 variant and BMI, both in men and in women. Body weight control and reduction in BMI are recommended in high-risk patients with the ABCG2 rs2231142 risk T allele.

Genetic and Physiological Effects of Insulin on Human Urate Homeostasis

Insulin and hyperinsulinemia reduce renal fractional excretion of urate (FeU) and play a key role in the genesis of hyperuricemia and gout, via uncharacterized mechanisms. To explore this association further we studied the effects of genetic variation in insulin-associated pathways on serum urate (SU) levels and the physiological effects of insulin on urate transporters. We found that urate-associated variants in the human insulin (INS), insulin receptor (INSR), and insulin receptor substrate-1 (IRS1) loci associate with the expression of the insulin-like growth factor 2, IRS1, INSR, and ZNF358 genes; additionally, we found genetic interaction between SLC2A9 and the three loci, most evident in women. We also found that insulin stimulates the expression of GLUT9 and increases [14C]-urate uptake in human proximal tubular cells (PTC-05) and HEK293T cells, transport activity that was effectively abrogated by uricosurics or inhibitors of protein tyrosine kinase (PTK), PI3 kinase, MEK/ERK, or p38 MAPK. Heterologous expression of individual urate transporters in Xenopus oocytes revealed that the [14C]-urate transport activities of GLUT9a, GLUT9b, OAT10, OAT3, OAT1, NPT1 and ABCG2 are directly activated by insulin signaling, through PI3 kinase (PI3K)/Akt, MEK/ERK and/or p38 MAPK. Given that the high-capacity urate transporter GLUT9a is the exclusive basolateral exit pathway for reabsorbed urate from the renal proximal tubule into the blood, that insulin stimulates both GLUT9 expression and urate transport activity more than other urate transporters, and that SLC2A9 shows genetic interaction with urate-associated insulin-signaling loci, we postulate that the anti-uricosuric effect of insulin is primarily due to the enhanced expression and activation of GLUT9.

Uric acid participating in female reproductive disorders: a review

Uric acid (UA) is the end metabolic product of purine metabolism. Early on, UA was considered to be a metabolite with a certain antioxidant capacity. As research has progressed, other properties of UA have been explored, and its association with many diseases has been found. The association between UA and kidney disease and cardiovascular disease is well established; however, there is still a paucity of reviews on the association between UA and the female reproductive system. An increasing number of epidemiological studies have shown elevated serum UA levels in patients with polycystic ovary syndrome (PCOS), endometriosis, etc. Additionally, serum UA can be used as a predictor of pregnancy complications and adverse foetal outcomes. An increasing number of animal experiments and clinical studies have revealed possible mechanisms related to the involvement of UA in certain female reproductive disorders: oxidative stress, chronic inflammation, mitochondrial dysfunction, etc. This article reviews the current mainstream mechanisms regarding the pathogenesis of UA and the role of UA in certain specific female reproductive disorders (direct involvement in the development of certain diseases or enhancement of other risk factors) in the hope of contributing to clinical prevention, diagnosis, treatment and improvement in prognosis.

Effects of Dietary Patterns on Serum Urate: Results From a Randomized Trial of the Effects of Diet on Hypertension

OBJECTIVE

To determine whether the Dietary Approaches to Stop Hypertension (DASH) diet or an alternative, simplified diet, emphasizing high-fiber fruits and vegetables (the FV diet), lowers serum urate levels.

METHODS

We conducted a secondary study of the DASH feeding study, a 3-arm, parallel-design, randomized trial of 459 adults with systolic blood pressure (BP) of <160 mm Hg and diastolic BP of 80-95 mm Hg, who were not receiving BP medications. Participants were randomized to receive 8 weeks of monitored feeding and ate 1 of 3 diets: 1) a typical American diet (control), 2) the FV diet, a diet rich in fruits and vegetables but otherwise similar to the control diet, or 3) the DASH diet, which was rich in fruits, vegetables, and low-fat dairy products, and reduced in fat, saturated fat, and cholesterol. Body weight was kept constant throughout the study. Serum urate levels were measured at baseline and after 8 weeks of feeding.

RESULTS

For the 327 participants with available specimens (mean ± SD age 45.4 ± 11.0 years, 47% women, 50% African American), the mean ± SD baseline serum urate level was 5.7 ± 1.5 mg/dl. Compared to the control diet, the FV diet reduced the mean serum urate level by 0.17 mg/dl (95% confidence interval [95% CI] -0.34, 0.00; P = 0.051) and the DASH diet reduced the mean serum urate level by 0.25 mg/dl (95% CI -0.43, -0.08; P = 0.004). These effects increased with increasing baseline serum urate levels (<5, 5-5.9, 6-6.9, 7-7.9, and ≥8 mg/dl) for those receiving the DASH diet (a reduction of 0.08, 0.12, 0.42, 0.44, and 0.73 mg/dl, respectively; P for trend = 0.04), but not for those receiving the FV diet.

CONCLUSION

Our findings indicate that the DASH diet reduces serum urate levels, particularly among those with hyperuricemia. These findings support the growing need for a dedicated trial to test the DASH diet among patients with hyperuricemia and gout.

Risk of gout among Taiwanese adults with ALDH-2 rs671 polymorphism according to BMI and alcohol intake

BACKGROUND

Gout stems from both modifiable and genetic sources. We evaluated the risk of gout among Taiwanese adults with aldehyde dehydrogenase-2 (ALDH2) rs671 single nucleotide polymorphism (SNP) according to body mass index (BMI) and alcohol drinking.

METHODS

We obtained information of 9253 individuals having no personal history of cancer from the Taiwan Biobank (2008-2016) and estimated the association between gout and independent variables (e.g., rs671, BMI, and alcohol drinking) using multiple logistic regression.

RESULTS

Alcohol drinking and abnormal BMI were associated with a higher risk of gout whereas the rs671 GA+AA genotype was associated with a lower risk. The odds ratios (ORs) and 95% confidence intervals (CIs) were 1.297 and 1.098-1.532 for alcohol drinking, 1.550 and 1.368-1.755 for abnormal BMI, and 0.887 and 0.800-0.984 for GA+AA. The interaction between BMI and alcohol on gout was significant for GG (p-value = 0.0102) and GA+AA (p-value = 0.0175). When we stratified genotypes by BMI, alcohol drinking was significantly associated with gout only among individuals with a normal BMI (OR; 95% CI = 1.533; 1.036-2.269 for GG and 2.109; 1.202-3.699 for GA+AA). Concerning the combination of BMI and alcohol drinking among participants stratified by genotypes (reference, GG genotype, normal BMI, and no alcohol drinking), the risk of gout was significantly higher in the following categories: GG, normal BMI, and alcohol drinking (OR, 95% CI = 1.929, 1.385-2.688); GG, abnormal BMI, and no alcohol drinking (OR, 95% CI, = 1.721, 1.442-2.052); GG, abnormal BMI, and alcohol drinking (OR, 95% CI = 1.941, 1.501-2.511); GA+AA, normal BMI, and alcohol drinking (OR, 95% CI = 1.971, 1.167-3.327); GA+AA, abnormal BMI, and no alcohol drinking (OR, 95% CI = 1.498, 1.256-1.586); and GA+AA, abnormal BMI, and alcohol drinking (OR, 95% CI = 1.545, 1.088-2.194).

CONCLUSIONS

Alcohol and abnormal BMI were associated with a higher risk of gout, whereas the rs671 GA+AA genotype was associated with a lower risk. Noteworthy, BMI and alcohol had a significant interaction on gout risk. Stratified analyses revealed that alcohol drinking especially among normal-weight individuals might elevate the risk of gout irrespective of the genotype.

The importance of including uric acid in the definition of metabolic syndrome when assessing the mortality risk

Introduction

Serum uric acid (SUA) has been depicted as a contributory causal factor in metabolic syndrome (MS), which in turn, portends unfavourable prognosis.

Aim

We assessed the prognostic role of SUA in patients with and without MS.

Methods

We used data from the multicentre Uric Acid Right for Heart Health study and considered cardiovascular mortality (CVM) as death due to fatal myocardial infarction, stroke, sudden cardiac death, or heart failure.

Results

A total of 9589 subjects (median age 58.5 years, 45% males) were included in the analysis, and 5100 (53%) patients had a final diagnosis of MS. After a median follow-up of 142 months, we observed 558 events. Using a previously validated cardiovascular SUA cut-off to predict CVM (> 5.1 mg/dL in women and 5.6 mg/dL in men), elevated SUA levels were significantly associated to a worse outcome in patients with and without MS (all p < 0.0001) and provided a significant net reclassification improvement of 7.1% over the diagnosis of MS for CVM (p = 0.004). Cox regression analyses identified an independent association between SUA and CVM (Hazard Ratio: 1.79 [95% CI, 1.15–2.79]; p < 0.0001) after the adjustment for MS, its single components and renal function. Three specific combinations of the MS components were associated with higher CVM when increasing SUA levels were reported, and systemic hypertension was the only individual component ever-present (all p < 0.0001).

Conclusion

Increasing SUA levels are associated with a higher CVM risk irrespective of the presence of MS: a cardiovascular SUA threshold may improve risk stratification.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-021-01815-0.

Uric acid-induced pancreatic β-cell dysfunction

Hyperuricemia is associated with insulin resistance, pancreatic β-cell dysfunction and consequently with development of type 2 diabetes. Although a direct relationship between high levels of uric acid (UA) and the development of diabetes is still a controversial issue, there is some evidence that strongly points to pancreatic β-cells damage as a result of high serum UA levels. Here, the mechanisms underlying UA-induced β-cell damage are discussed. Available literature indicates that UA can decrease glucose-stimulated insulin secretion and cause β-cell death. The mechanisms underlying these effects are UA-induced oxidative stress and inflammation within the β-cells. UA also stimulates inducible nitric oxide (NO) synthase (iNOS) gene expression leading to NO-induced β-cell dysfunction. Thus hyperuricemia may potentially cause β-cell dysfunction, leading to diabetes. It may be hypothesized that in hyperuricemic subjects, UA-lowering drugs may be beneficial in preventing diabetes.

Daily consumption effects of probiotic yogurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 on oxidative stress in metabolic syndrome patients

BACKGROUND AND AIMS

Available evidence substantiates a strong association between metabolic syndrome and elevated oxidative stress. This study was aimed to assess the effects of probiotic yogurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 on the oxidative stress biomarkers in patients with metabolic syndrome. Furthermore, the association between uric acid levels and insulin resistance indexes was assessed.

METHODS

An 8-week randomized, double-blind, placebo-controlled, parallel study was designed. Forty-four patients, 22 males and 22 females aged 20-65 years, were assigned into two groups. Treatment (n = 22) and control (n = 22) groups consumed 300 g/d of probiotic and regular yogurt, respectively. The serum concentration of uric acid, oxidized Low-Density Lipoprotein (oxLDL), Malondialdehyde (MDA) and Total Antioxidant Capacity (TAC) were measured at the beginning and the end of the trial. This study was recorded at http://www.irct.ir (code: IRCT201608213140N17).

RESULTS

Probiotic yogurt consumption resulted in a significant decrease in the level of serum uric acid and a significant increase in the level of TAC (p < 0.05). A positive significant association between uric acid with insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) and an inverse significant relationship with insulin sensitivity (Quicki) were also found (p < 0.05).

CONCLUSION

Probiotic yogurt consumption through improvement in insulin sensitivity may exert positive effects on the oxidative stress and uric acid levels. However, further studies are needed to make concise conclusions.

The effect of baseline serum uric acid on chronic kidney disease in normotensive, normoglycemic, and non-obese individuals: A health checkup cohort study

Introduction

The independent role of serum uric acid (SUA) on kidney disease is controversial due to its association with metabolic syndrome. The objective of this study was to investigate the association of baseline SUA with development of chronic kidney disease and eGFR decline in normotensive, normoglycemic and non-obese individuals during follow up period.

Materials and methods

We included non-hypertensitive, non-diabetic, and non-obese 13,133 adults with estimated glomerular filtration rate (eGFR) ≥ 60ml/min/1.73m² who had a voluntary health check-up during 2004–2017.

Results

SUA was positively related to adjusted means of systolic blood pressure (SBP), triglyceride, body mass index, and body fat percent. SUA was inversely associated with high density lipoprotein HDL (P for trend ≤0.001). SUA was an independent risk factor for the development of diabetes, hypertension, and obesity. During 45.0 [24.0–76.0] months of median follow up, the highest quartiles of SUA showed significant risks of 30% eGFR decline compared than the lowest quartile (RR:3.701; 95% CI: 1.504–9.108). The highest quartile had a 2.2 fold (95% CI: 1.182–4.177) increase in risk for incident chronic kidney disease (CKD).

Conclusions

SUA is an independent risk factor for the development of diabetes, hypertension, and obesity in the healthy population. High SUA is associated with increased risk of CKD development and eGFR decline in participants with intact renal function.

Effect of body mass index on serum urate and renal uric acid handling responses to an oral inosine load: experimental intervention study in healthy volunteers

Background

High body mass index (BMI) is strongly associated with hyperuricaemia. It is unknown whether overweight and obesity influences serum urate primarily through increased urate production or reduced renal clearance of uric acid. The aim of this study was to determine the influence of BMI on the response to inosine, a purine nucleoside that functions as an intermediate in the purine salvage and degradation pathways.

Methods

Following an overnight fast, 100 healthy participants without gout attended a study visit. Blood and urine samples were taken prior to and over 180 min after 1.5 g oral inosine. Serum urate and fractional excretion of uric acid (FEUA) were analysed according to high BMI (≥ 25 kg/m²) and low/normal BMI (< 25 kg/m²) groups, and according to BMI as a continuous variable.

Results

Participants in the high BMI group (n = 52, mean BMI 30.8 kg/m²) had higher serum urate concentrations at baseline (P = 0.002) compared to those with low/normal BMI (mean BMI 21.8 kg/m²). However, the high BMI group had a smaller increase in serum urate following the inosine load (P = 0.0012). The two BMI groups had a similar FEUA at baseline (P = 0.995), but those in the high BMI group had a smaller increase in FEUA following the inosine (P = 0.0003). Similar findings were observed when analysing BMI as a continuous variable. Those with high BMI had a smaller increase in FEUA per increase in serum urate, compared to those with low BMI (P = 0.005).

Conclusions

In a fasting state, people with high BMI have elevated serum urate levels but similar FEUA values compared with those with low/normal BMI. Following a purine load, those with high BMI have an attenuated renal excretion of uric acid. These data, using an experimental method to dynamically assess human urate handling, suggest that people with high BMI have a higher renal capacity for uric acid reabsorption when fasted and following a dietary purine intake have reduced renal clearance.

Trial registration

Australia and New Zealand Clinical Trials Registry, ACTRN12615001302549, date of registration 30 November 2015.

Renal effects of uric acid: hyperuricemia and hypouricemia

The prevalence of chronic kidney disease (CKD) is increasing worldwide. Although hyperuricemia has been associated with CKD in many studies, it remains controversial whether this is the cause or the result of decreased renal function. Recent observational studies of healthy populations and patients with CKD have reported that uric acid (UA) has an independent role in the development or progression of CKD. Experimental studies have shown several potential mechanisms by which hyperuricemia may cause or promote CKD. However, other reports have indicated an association between hypouricemia and CKD. This opposing effect is hypothesized to occur because UA is a major antioxidant in human plasma and is associated with oxidative stress. In this article, we discuss the potential association between UA imbalance and CKD and how they can be treated.

Effects of Low-Fat, Mediterranean, or Low-Carbohydrate Weight Loss Diets on Serum Urate and Cardiometabolic Risk Factors: A Secondary Analysis of the Dietary Intervention Randomized Controlled Trial (DIRECT)

OBJECTIVE

Weight loss diets may reduce serum urate (SU) by lowering insulin resistance while providing cardiometabolic benefits, something urate-lowering drugs have not shown in trials. We aimed to examine the effects of weight loss diets on SU and cardiometabolic risk factors.

RESEARCH DESIGN AND METHODS

This secondary study of the Dietary Intervention Randomized Controlled Trial (DIRECT) used stored samples from 235 participants with moderate obesity randomly assigned to low-fat, restricted-calorie (n = 85); Mediterranean, restricted-calorie (n = 76); or low-carbohydrate, non-restricted-calorie (n = 74) diets. We examined SU changes at 6 and 24 months overall and among those with hyperuricemia (SU ≥416 μmol/L), a relevant subgroup at risk for gout.

RESULTS

Among all participants, average SU decreases were 48 μmol/L at 6 months and 18 μmol/L at 24 months, with no differences between diets (P > 0.05). Body weight, HDL cholesterol (HDL-C), total cholesterol:HDL-C ratio, triglycerides, and insulin concentrations also improved in all three groups (P < 0.05 at 6 months). Adjusting for covariates, changes in weight and fasting plasma insulin concentrations remained associated with SU changes (P < 0.05). SU reductions among those with hyperuricemia were 113, 119, and 143 μmol/L at 6 months for low-fat, Mediterranean, and low-carbohydrate diets (all P for within-group comparison < 0.001; P > 0.05 for between-group comparisons) and 65, 77, and 83 μmol/L, respectively, at 24 months (all P for within-group comparison < 0.01; P > 0.05 for between-group comparisons).

CONCLUSIONS

Nonpurine-focused weight loss diets may simultaneously improve SU and cardiovascular risk factors likely mediated by reducing adiposity and insulin resistance. These dietary options could provide personalized pathways to suit patient comorbidity and preferences for adherence.

Pathophysiology of hyperuricemia and its clinical significance - a narrative review

Hyperuricemia, i.e. increased serum uric acid (UA) concentration, is a common problem in clinical practice. While there are clear guidelines concerning management of symptomatic hyperuricemia in acute conditions such as gout, urolithiasis or acute urate nephropathy, less is known about their secondary prevention. Moreover, despite the ongoing debate on the role of UA in the pathogenesis of chronic kidney disease, hypertension, cardiovascular disease and heart failure, the management of asymptomatic hyperuricemia in patients with these chronic conditions is still mainly up to physicians' judgement. Individual considerations should always be taken into account when prescribing urate-lowering therapy. In this narrative review study, we attempt to present current trends concerning treatment of patients with either symptomatic or asymptomatic hyperuricemia in the light of the available knowledge on the role of hyperuricemia in the development of gout, renal, cardiovascular and other diseases.

Differences among patients with and without nonalcoholic fatty liver disease having elevated alanine aminotransferase levels at various stages of metabolic syndrome

Background

The prevalence of nonalcoholic fatty liver disease (NAFLD) in the non-obese population has increased and NAFLD is not always recognized in individuals with metabolic syndrome (MS). The risk of cirrhosis is higher in patients having NAFLD with elevated alanine aminotransferase (ALT) levels than in those having NAFLD with normal ALT levels.

Objective

To measure the differences in clinical factors associated with NAFLD having elevation of ALT among subjects with Non-MS, Pre-MS, and MS, and to measure differences in metabolites between MS subjects with and without NAFLD having elevation of ALT.

Methods

Among 7,054 persons undergoing health check-ups, we included 3,025 subjects who met the selection criteria. We measured differences in clinical factors for NAFLD having elevation of ALT among subjects with Non-MS, Pre-MS, and MS, and compared metabolites between subjects with and without NAFLD having elevation of ALT in 32 subjects with MS.

Results

The prevalence of NAFLD and NAFLD having elevation of ALT was significantly progressively greater in subjects with Non-MS, Pre-MS, and MS (p <0.001, respectively). In the Non-MS group, there were significant differences between subjects with and without NAFLD having elevation of ALT with respect to body mass index (BMI), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, hemoglobin A1c, uric acid, aspartate aminotransferase (AST); In the Pre-MS group, there were significant differences in BMI, hypertension, AST, and gamma-glutamyl transpeptidase (GGT); In the MS group, there were significant differences in HDL-C, impaired glucose tolerance, AST, and GGT. There were significant differences in levels of metabolites of nicotinamide, inosine, and acetyl-L-carnitine between MS subjects with and without NAFLD having elevation of ALT (all p <0.05).

Conclusions

Although NAFLD having elevation of ALT is important for development of NAFLD, differences in factors associated with NAFLD having elevation of ALT at various stages of MS should be considered. Additionally, several metabolites may play roles in the identification of risk for NAFLD in individuals with MS.

Whole genome sequence analysis identifies a PAX2 mutation to establish a correct diagnosis for a syndromic form of hyperuricemia

Hereditary hyperuricemia may occur as part of a syndromic disorder or as an isolated nonsyndromic disease, and over 20 causative genes have been identified. Here, we report the use of whole genome sequencing (WGS) to establish a diagnosis in a family in which individuals were affected with gout, hyperuricemia associated with reduced fractional excretion of uric acid, chronic kidney disease (CKD), and secondary hyperparathyroidism, that are consistent with familial juvenile hyperuricemic nephropathy (FJHN). However, single gene testing had not detected mutations in the uromodulin (UMOD) or renin (REN) genes, which cause approximately 30-90% of FJHN. WGS was therefore undertaken, and this identified a heterozygous c.226G>C (p.Gly76Arg) missense variant in the paired box gene 2 (PAX2) gene, which co-segregated with renal tubulopathy in the family. PAX2 mutations are associated with renal coloboma syndrome (RCS), which is characterized by abnormalities in renal structure and function, and anomalies of the optic nerve. Ophthalmological examination in two adult brothers affected with hyperuricemia, gout, and CKD revealed the presence of optic disc pits, consistent with optic nerve coloboma, thereby revising the diagnosis from FJHN to RCS. Thus, our results demonstrate the utility of WGS analysis in establishing the correct diagnosis in disorders with multiple etiologies.