Potential causal associations between vitamin D and uric acid: Bidirectional mediation analysis

Uric Acid Correlates with Serum Levels of Mineral Bone Metabolism and Inflammation Biomarkers in Patients with Stage 3a-5 Chronic Kidney Disease

Background and Objectives: Uric acid (UA) and the markers of mineral bone metabolism and inflammation are commonly altered in patients with chronic kidney disease (CKD) and are associated with the risk of cardiovascular complications and death. Studies point to a link between high serum UA and mineral bone homeostasis and inflammation, but controversy remains. The aim of this study was to evaluate the relationship between UA levels and mineral bone metabolism and inflammation biomarkers in a sample of Mexican patients with CKD 3a-5. Materials and Methods: This cross-sectional study included 146 Mexican patients with CKD 3a-5. In addition, 25 healthy subjects were included in the study with the aim of generating reference data for comparisons. Metabolic parameters including UA serum concentrations, mineral bone metabolism (parathormone (PTH), fibroblast growth factor 23 (FGF23), calcium, and phosphate), and inflammation (interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α)) biomarkers were measured in all of the samples and compared as a function of the estimated glomerular function rate (eGFR) or UA levels. Results: Intact PTH, FGF23, and cytokines were higher in advanced CKD stages. Patients with hyperuricemia had significantly higher values of FGF23 and TNF-α compared with those without hyperuricemia. The eGFR was found to be significantly and negatively correlated with all markers. Uric acid was significantly correlated with phosphate, iPTH, FGF23, and TNF-α, whereas iPTH was significantly correlated with FGF23, TNF-α, and FGF23. Finally, a multivariate analysis confirmed the relationship of eGFR with all the tested biomarkers, as well as other relationships of iPTH with UA and TNF-α and of FGF23 with UA and TNF-α. Conclusions: This study supports the relationship between uric acid and levels of mineral bone metabolism and inflammation biomarkers in patients with CKD at middle to advanced stages. In the follow-up of patients with CKD, monitoring and controlling UA levels through nutritional or pharmacological interventions could help in the prevention of alterations related to mineral bone metabolism.

Association between 25 hydroxyvitamin D and serum uric acid level in the Chinese general population: a cross-sectional study

BACKGROUD

The relationship between serum uric acid (SUA) and 25-hydroxyvitamin D (25(OH)D) has been variably characterized in existing literature, with inconsistent results regarding its nature and implications in the Chinese population. This study aims to clarify this association, considering the potential impact of vitamin D levels on SUA.

METHODS

This cross-sectional study involved 7,086 individuals from the Second Affiliated Hospital of Zhejiang University School of Medicine, screened throughout 2020. We collected data on 25(OH)D, SUA, and other metabolic markers. Logistic regression models adjusted for confounding factors were utilized to analyze the relationships.

RESULTS

Our findings illustrate a statistically significant inverted U-shaped relationship between 25(OH)D and SUA. The identified threshold effect at 28.82 ng/ml is pivotal; with 25(OH)D levels below this point associated with an increased risk of hyperuricemia (odds ratio: 1.0146, p = 0.0148), and levels above it offering protective benefits (odds ratio: 0.9616, p = 0.0164).

CONCLUSIONS

Our findings confirm a nonlinear, inverted U-shaped correlation between 25(OH)D and SUA, emphasizing the importance of maintaining vitamin D levels within a specific range to effectively manage hyperuricemia. These results support the implementation of personalized vitamin D supplementation strategies to optimize metabolic health outcomes, highlighting the complex interplay between vitamin D status and uric acid levels.

Correlation between Vitamin D and Uric Acid in Menopausal Women

Background : Vitamin D deficiency and hyperuricemia are global health problems in post-menopausal women in which parathyroid hormone increases hyperuricemia incidence. Aim : This research purpose to  determine correlation between vitamin D and uric acid levels in postmenopausal women Methods: This research is an observational analytic study with a cross-sectional study design conducted at University of North Sumatra Hospital and Network Hospital in Medan for 12 months on 40 postmenopausal women who met inclusion and exclusion criteria. The data will be analyzed descriptively to determine variables frequency distribution. Previously, normality test of numerical data is carried out. If the data is normally distributed, Pearson correlation test will be carried out, and if the data is not normally distributed, then Spearman correlation test will be used. Results : Mean vitamin D of the sample was 23.11 ng/mL with a standard deviation 4.43 and median value 23.5 ng/mL. while the mean uric acid was 7.52 mg/dL with a standard deviation 0.92 and median value 7.45 mg/dL. There is an inverse relationship between uric acid levels and Vitamin D, as evidenced by Pearson test correlation coefficient of -0.541 with p value = 0.001. Conclusion : There is an inverse correlation between Vitamin D and uric acid levels.

Hyperuricemia is associated with secondary hyperparathyroidism in patients with chronic kidney disease

PURPOSE

Hyperuricemia is common among patients with chronic kidney disease (CKD). In the general population, hyperuricemia is associated with secondary hyperparathyroidism (SHPT), in a mechanism that involves vitamin D metabolism. Data for patients with CKD, however, are scarce. We aimed to evaluate the relationship between hyperuricemia and mineral and bone metabolism, particularly hyperparathyroidism.

METHODS

This is a retrospective study that included 922 adult patients with stages 3, 4, or 5 CKD, not on dialysis. Clinical, demographic, and biochemical data were collected from charts and included uric acid, parathyroid hormone (PTH), 25(OH)-vitamin D, calcium, phosphate, renal function (estimated glomerular filtration rate-eGFR), and medications such as allopurinol, furosemide, and cholecalciferol. SHPT was defined as PTH > 65 pg/ml.

RESULTS

Our patients were mostly Caucasian women, with a mean age of 64 ± 16 years. SHPT and hyperuricemia were observed in 70% and 62.4% of patients, respectively. Patients with SHPT presented higher levels of uric acid (7.2 ± 1.8 vs. 6.6 ± 1.7 mg/dL, p = 0.0001) and a higher frequency of hyperuricemia (66% vs. 33%, p = 0.0001). Patients with hyperuricemia were mostly female, with lower eGFR, higher phosphate, and higher PTH. The risk of hypovitaminosis D was higher among patients with SHPT (69.7% vs. 53.1%, p = 0.0001). Hyperuricemia remained independently associated with hyperparathyroidism, (p = 0.033) even after adjustments for eGFR, calcium, phosphate, hypovitaminosis D, and use of allopurinol, calcitriol, furosemide, and cholecalciferol.

CONCLUSION

Hyperuricemia seems to be a contributing factor for SHPT in patients with CKD. The mechanisms behind this finding have yet to be elucidated.

Vitamin D pathway gene variation rs3740165 is associated with serological uric acid levels in healthy Chinese women

AIM

To investigate the relationship between gene polymorphisms involved in the vitamin D metabolic pathway and serum uric acid (UA) levels in Chinese women.

METHODS

Fifteen key genes within the vitamin D metabolic pathway were screened using 96 single nucleotide polymorphisms in a group of 1,206 (37.96 ± 13.08 years) unrelated healthy Chinese women (aged 20-85 years). Blood and urine tests were performed at the same time. The Wilcoxon Mann-Whitney test was used to compare groups aged ≤50 years and >50 years. The mean serum UA values were computed within each group of homozygous referent, heterozygous, and homozygous variant genotypes for each single nucleotide polymorphism.

RESULTS

The exclusion process left 1,169 participants (38.16 ± 13.13 years) for analysis. One single nucleotide polymorphism in the CUBN gene (rs3740165) was identified as being significantly associated with serum UA levels in the group aged over 50 years. The wild type (C/C) population had higher serum UA levels in this group (P<0.001). In women aged over 50 years, allele C was associated with a higher risk of hyperuricemia than allele T (odds ratio 2.752, 95% confidence interval 1.458-5.192; P = 0.002). There was also a higher risk of hyperuricemia in genotype TC + CC compared with genotype TT (odds ratio 3.326, 95% confidence interval 1.513-7.313; P = 0.003) in women over 50 years of age.

CONCLUSION

The results suggest that the CUBN gene contributes to variability in serum UA levels in healthy Chinese Han women over 50 years of age.

Unveiling Genetic Variants Underlying Vitamin D Deficiency in Multiple Korean Cohorts by a Genome-Wide Association Study

BACKGROUND

Epidemiological data have shown that vitamin D deficiency is highly prevalent in Korea. Genetic factors influencing vitamin D deficiency in humans have been studied in Europe but are less known in East Asian countries, including Korea. We aimed to investigate the genetic factors related to vitamin D levels in Korean people using a genome-wide association study (GWAS).

METHODS

We included 12,642 subjects from three different genetic cohorts consisting of Korean participants. The GWAS was performed on 7,590 individuals using linear or logistic regression meta- and mega-analyses. After identifying significant single nucleotide polymorphisms (SNPs), we calculated heritability and performed replication and rare variant analyses. In addition, expression quantitative trait locus (eQTL) analysis for significant SNPs was performed.

RESULTS

rs12803256, in the actin epsilon 1, pseudogene (ACTE1P) gene, was identified as a novel polymorphism associated with vitamin D deficiency. SNPs, such as rs11723621 and rs7041, in the group-specific component gene (GC) and rs11023332 in the phosphodiesterase 3B (PDE3B) gene were significantly associated with vitamin D deficiency in both meta- and mega-analyses. The SNP heritability of the vitamin D concentration was estimated to be 7.23%. eQTL analysis for rs12803256 for the genes related to vitamin D metabolism, including glutamine-dependent NAD(+) synthetase (NADSYN1) and 7-dehydrocholesterol reductase (DHCR7), showed significantly different expression according to alleles.

CONCLUSION

The genetic factors underlying vitamin D deficiency in Korea included polymorphisms in the GC, PDE3B, NADSYN1, and ACTE1P genes. The biological mechanism of a non-coding SNP (rs12803256) for DHCR7/NADSYN1 on vitamin D concentrations is unclear, warranting further investigations.

The Mediation Effects of Aluminum in Plasma and Dipeptidyl Peptidase Like Protein 6 (DPP6) Polymorphism on Renal Function via Genome-Wide Typing Association

Aluminum (Al) toxicity is related to renal failure and the failure of other systems. Although there were some genome-wide association studies (GWAS) in Australia and England, there were no GWAS about Han Chinese to our knowledge. Thus, this research focused on using whole genomic genotypes from the Taiwan Biobank for exploring the association between Al concentrations in plasma and renal function. Participants, who underwent questionnaire interviews, biomarkers, and genotyping, were from the Taiwan Biobank database. Then, we measured their plasma Al concentrations with ICP-MS in the laboratory at Kaohsiung Medical University. We used this data to link genome-wide association (GWA) tests while looking for candidate genes and associated plasma Al concentration to renal function. Furthermore, we examined the path relationship between Single Nucleotide Polymorphisms (SNPs), Al concentrations, and estimated glomerular filtration rates (eGFR) through the mediation analysis with 3000 replication bootstraps. Following the principles of GWAS, we focused on three SNPs within the dipeptidyl peptidase-like protein 6 (DPP6) gene in chromosome 7, rs10224371, rs2316242, and rs10268004, respectively. The results of the mediation analysis showed that all of the selected SNPs have indirectly affected eGFR through a mediation of Al concentrations. Our analysis revealed the association between DPP6 SNPs, plasma Al concentrations, and eGFR. However, further longitudinal studies and research on mechanism are in need. Our analysis was still be the first study that explored the association between the DPP6, SNPs, and Al in plasma affecting eGFR.

Vitamin D in pediatric patients with obesity and arterial hypertension

The purpose of this study was to find potential differences in vitamin D levels between different groups: overweight children with hypertension, normal-weight children with hypertension, overweight children with normal blood pressure and normal-weight children without hypertension, representing the control group. We also wanted to determine whether there are correlations between vitamin D levels and other clinical laboratory parameters, to evaluate the potential need for substitution. We measured vitamin D, homocysteine, total cholesterol, HDL, LDL, triglycerides, uric acid, glucose, apolipoprotein A1, apolipoprotein B, alkaline phosphatase, calcium, phosphate and magnesium serum levels in all groups. We also took anthropometric measurements (body weight, height, body mass index (BMI)) and observed patients' blood pressure. The results were analyzed with SPSS statistic tool with basic statistical methods. The study included 175 children between 5 and 18 years of age. Fiftyseven were healthy (group A-control group), 41 normal-weight with hypertension (group B), 44 overweight with hypertension (group C) and 33 overweight with normal blood pressure (group D). The results showed statistically significant differences in values of vitamin D between all groups-A and B (p = 0.003), A and C (p < 0.001), A and D (p < 0.001), B and D (p = 0.043), B and C (0.030), except for groups C and D (p = 0.830). There were statistically significant correlations between vitamin D and BMI (r = - 0.196, p = 0.010), systolic pressure (r = - 0.190, p = 0.002), diastolic pressure (r = - 0.149, p = 0.050), homocysteine (r = - 0.208, p = 0.007), triglycerides (r = - 0.196, p = 0.011) and apolipoprotein A1 (r = 0.222, p = 0.007), confirmed in multivariate model. For the blood pressure, the higher the systolic blood pressure, the lower the average vitamin D was. The pilot study shows significant differences in serum vitamin D levels between all groups of children, apart from groups C and D. These results, combined with statistically significant correlations between vitamin D and systolic and diastolic blood pressure suggest the need for monitoring and potential substitution of vitamin D in in pediatric patients with hypertension.

Urine and Serum Electrolytes and Biochemical Values Associated with Osteoporosis in Premenopausal and Postmenopausal Women: A Longitudinal and Cross-Sectional Study Using Korean Genome and Epidemiology Study (KoGES) Cohort

Osteoporosis is a major public health concern, especially in women. This study aims to identify early biomarkers from biochemical measurements of serum and urine for recognizing the development of osteoporosis and osteopenia in premenopausal and postmenopausal women. From the Korean Genome and Epidemiology Study (KoGES) cohort, longitudinal study participants with normal bone density were enrolled and assessed for the association of baseline clinical and biochemical factors with osteoporosis development over 4 years. In addition, a cross-sectional study between normal bone density and osteopenia/osteoporosis was conducted to validate the risk factors found in the longitudinal cohort. Of the 5272 female participants in the KoGES cohort, 813 women (501 premenopausal and 312 menopausal) who had normal bone density at baseline were included in the longitudinal study. During the 4 years of follow-up, 64 patients developed osteoporosis and 354 developed osteopenia. In a multivariate logistic regression analysis, serum calcium and urine uric acid levels were significantly associated with elevated osteoporosis risk in premenopausal and postmenopausal women, respectively (risk of osteoporosis by serum calcium levels in premenopausal women: 4.03 (1.09–14.93), p = 0.037; risk of osteoporosis by urine uric acid levels in postmenopausal women: 24.08 (1.79–323.69), p = 0.016). For the cross-sectional study, serum and urine parameters were compared between women with osteopenia or osteoporosis at baseline and those with normal bone density. Urine uric acid levels were found to be significantly higher in both premenopausal and postmenopausal women with bone loss than in women with normal bone density (p < 0.001 and p = 0.004, respectively). Uric acid level in urine may be an early marker for the development of osteoporosis in women, especially after menopause.

Vitamin D supplementation is associated with serum uric acid concentration in patients with prediabetes and hyperuricemia

Aims

Vitamin D deficiency is associated with a number of noncommunicable conditions. We conducted a randomised controlled trial to determine the effect of vitamin D supplementation on serum uric acid concentration in patients with prediabetes, in whom hyperuricaemia is common.

Methods

Seventy-one volunteers (35–80 years), with impaired fasting glucose and/or impaired glucose tolerance were randomised to three groups, vitamin D₃, vitamin D₂ and control, and followed for 12 months.

Results

After 12 weeks, vitamin D supplementation was associated with a reduction in serum uric acid concentration in participants with baseline uric acid concentration > 6 mg/dL, but no significant change was observed in controls. We then assessed the dose–response relationship between vitamin D supplementation and the change in serum uric acid concentration and found that the change in serum total 25-hydroxyvitamin D did not correlate with the change in serum uric acid that occurred during vitamin D supplementation. The factors associated with larger reductions in serum uric acid were a higher baseline serum uric acid and a larger increase in serum 1,25-dihydroxyvitamin D.

Conclusions

Vitamin D supplementation lowers serum uric acid in prediabetic patients with hyperuricaemia, and supplementation might be considered to help alleviate hyperuricaemia in these patients.

Association Between Vitamin D and Uric Acid in Adults: A Systematic Review and Meta-Analysis

Association between vitamin D and uric acid is complex and might be bidirectional. Our study aimed to determine the bidirectional association between vitamin D and uric acid in adults. Using MEDLINE via PubMed and Scopus, we systematically searched for observational or interventional studies in adults, which assessed the association between serum vitamin D and serum uric acid, extracted the data, and conducted analysis by direct and network meta-analysis. The present review included 32 studies, of which 21 had vitamin D as outcome and 11 had uric acid as outcome. Meta-analysis showed a significant pooled beta coefficient of serum uric acid level on serum 25(OH)D level from 3 studies of 0.512 (95% confidence interval: 0.199, 0.825) and a significant pooled odds ratio between vitamin D deficiency and hyperuricemia of 1.496 (1.141, 1.963). The pooled mean difference of serum 25(OH)D between groups with hyperuricemia and normouricemia was non-significant at 0.138 (-0.430, 0.707) ng/ml, and the pooled mean difference of serum uric acid between categories of 25(OH)D were also non-significant at 0.072 (-0.153, 0.298) mg/dl between deficiency and normal, 0.038 (-0.216, 0.292) mg/dl between insufficiency and normal, and 0.034 (-0.216, 0.283) mg/dl between deficiency and insufficiency. In conclusion, increasing serum uric acid might be associated with increasing 25(OH)D level, while vitamin D deficiency is associated with hyperuricemia. These reverse relationships should be further evaluated in a longitudinal study.

Female oxidative status in relation to calcium availability, metal pollution and offspring development in a wild passerine

Both Ca deficiency and metal exposure may affect physiological and nutritional condition of breeding females altering their ability to deposit essential resources (e.g. Ca, antioxidants) into the eggs. This effect of the maternal investment into egg quality is not strictly limited to the embryonic period, but may persist after hatching, since nutrient levels in yolks can compromise nestling antioxidant status, growth and fledging success. The goal of this study was to investigate how metal pollution and Ca availability during the breeding season affect oxidative stress biomarkers and plasma biochemistry in adult female pied flycatchers (Ficedula hypoleuca). In addition, we aim to evaluate how maternal antioxidant status and body condition relate to breeding parameters and offspring oxidative balance. Females breeding in a metal-polluted area in SW Finland showed higher metal concentrations compared to the control area, although current levels were below the toxic level able to affect female physiology. In addition, Ca availability was not constraining female oxidative status and general health in the study area. Interestingly, our results suggested that antioxidant response to metals was better when Ca concentrations were high enough to cover the physiological Ca requirements in breeding females. There seems to be a subtle balance between the concentrations of Ca in the organism and the tolerance to metal-related effects that requires further research. This study supports that offspring oxidative balance and nestling development are affected by maternal body condition and antioxidant status.

Association between serum uric acid and bone health in adolescents

Previous studies are suggestive of the protective role of uric acid on bone in the middle-aged and elderly. Whether this association exists in younger individuals has not been examined. This investigation showed a significant positive association between serum uric acid and bone parameters among Iranian adolescents.

INTRODUCTION

Uric acid (UA) might be linked to bone health, but it is unclear whether its effects on bone are limited to certain population subgroups. This study is aimed at investigating the correlation between serum uric acid levels and bone mineral density (BMD) in Iranian adolescents.

METHODS

This cross-sectional study was conducted on 413 (221 girls and 192 boys) Iranian adolescents aged 9-19 years. An analysis of anthropometric, biochemical parameters and bone density was performed on the participants. Measurements included serum uric acid, calcium, phosphorus, alkaline phosphatase, albumin, and vitamin D. They were divided according to their serum UA into the low UA group who had UA ≤ 6 mg/dL and the high UA group with UA > 6 mg/dL. BMD and bone mineral content (BMC) were measured in the total body, lumbar spine, and left femoral neck, using dual energy X-ray absorptiometry (DXA), and bone mineral apparent density (BMAD) was calculated.

RESULTS

A Pearson correlation analysis revealed a significant correlation between UA and bone parameters. In multiple regression analyses adjusted for potential confounders, serum UA was proven to be associated with BMD and BMC at all sites. There was no association between UA, serum calcium, and vitamin D concentrations.

CONCLUSION

Our study, as the first research on adolescents, demonstrated a higher bone density in those who had higher UA levels.

The Association of Serum Vitamin D Deficiency and Metabolic Risk Factors in Chinese Adults with Prediabetes: A Cross-Sectional Study

The association of serum vitamin D deficiency and metabolic risk factors in Chinese adults with prediabetes (PreDM) has not been investigated. The present study aimed to investigate the association of serum vitamin D deficiency and metabolic risk factors in Chinese adults with PreDM. In this cross-sectional study, we stratified 412 PreDM patients into vitamin D sufficient, vitamin D insufficient and vitamin D deficient subgroups. The physical examination data was collected. Serum 25-hydroxyvitamin D₃ [25(OH)D₃] were measured by high performance liquid chromatography. The prevalence of vitamin D deficiency and insufficiency in PreDM patients were 30.58% and 26.70%, respectively. Compared with the vitamin D deficient group, the prevalence of metabolic syndrome, central obesity, hyperglycemia and hypertension were higher than those in the vitamin D insufficient or sufficient group (p<0.05). Moreover, the prevalence of dyslipidemia in the vitamin D deficient group was higher than those in the vitamin D sufficient group (p<0.05). We observed an inverse relationship between 25(OH)D₃ levels and waist circumference, triglyceride, and serum uric acid (β=-0.315; β=-0.134; β=-0.239), a positive relationship between 25(OH)D₃ levels and high-density lipoprotein cholesterol (β=0.197) after adjusting for age, sex and body mass index. Vitamin D deficiency is very common among PreDM patients in China and this deficiency is related to metabolic risk factors.

Association of serum uric acid levels with primary open-angle glaucoma: a 5-year case-control study

PURPOSE

It has been hypothesised that uric acid (UA) has a protective effect against oxidative damage in the central nervous system. Therefore, we investigated serum UA concentrations in patients with primary open-angle glaucoma (POAG) and explored the relationship between serum UA concentration and glaucoma severity.

METHODS

This prospective, cross-sectional, case-control study was conducted in 163 POAG patients and 103 normal controls. Clinical and demographic information was obtained from the medical data platform of the Eye & ENT Hospital of Fudan University, Shanghai, China. The POAG patients were categorised into mild [median deviation (MD) ≤ 6.00 dB], moderate (MD > 6 Db-≥12 dB) and severe (MD > 12 dB) subgroups, based on their visual field MD results.

RESULTS

The level of serum UA in the POAG group (0.321 ± 0.084 mmol/l) was approximately 12.77% lower (p < 0.001) than that of the control group (0.362 ± 0.053 mmol/l). The UA/creatinine (Cr) ratio was approximately 14.99% lower (p < 0.001) in patients with POAG (4.47 ± 1.15), compared with the control group (5.14 ± 1.05). The mean level of UA was lowest in the severe POAG group, followed by the moderate POAG group, and the mild POAG group (p < 0.001). A similar trend was observed when UA levels were compared between the POAG and control groups in males. Multivariate regression analyses showed a significant negative correlation between UA and vertical cup-disc ratio (B = -0.320, p = 0.034), and UA and MD (B = -0.441, p = 0.031) in males.

CONCLUSION

Primary open-angle glaucoma patients have lower UA levels; however, a negative association between UA levels and disease severity was evident in male patients.

Uric Acid and Its Correlation with Various Metabolic Parameters: A Population-Based Study

INTRODUCTION

Uric acid, apparently an inert waste product, was found to have association with various metabolic disorders. The data regarding prevalence of serum uric acid (SUA) abnormalities and its correlation with other anthropo-metabolic parameters, however, are scanty.

MATERIALS AND METHODS

In all, 405 participants from a rural area were investigated for various metabolic parameters including uric acid. SUA level was evaluated for having any correlation with other anthropometric and metabolic disorders like obesity, dyslipidemia, metabolic syndrome (MetS), hypertension, calcium and vitamin D abnormalities, liver function, and glycemic alterations. Lean MetS is defined as those having waist criteria below the region specific waist criteria and even then satisfying the definition of MetS as per the National Cholesterol Education Program (NCEP) ATP-III (Adult Treatment Panel) criteria.

RESULTS

The mean uric acid was 4.2 mg/dL (±1.35), with 4.9 mg/dL (±1.28) for males and 3.7 mg/dL (±1.14) for females. Thirteen of 405 people (3.2%) found to have uric acid level of more than 7.0 mg/dL, and eight people out of 405 (2.0%) had hypouricemia. SUA showed correlation with age, blood pressure, and the anthropometric parameters for obesity, for example, weight, body mass index, waist circumference, waist hip ratio, waist height ratio, fasting insulin, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglycerides. However, fasting glucose, calcium, phosphate, 25-hydroxy vitamin D3, and iPTH did not show any correlation with the SUA level. Compared to the healthy population, SUA level was elevated in MetS as defined by International Diabetes Federation (IDF) criteria. However, the SUA in healthy population was not significantly different from the Lean MetS, and SUA of Lean MetS was not significantly different from Obese MetS.

CONCLUSION

SUA is elevated in MetS compared to the normal population. However, SUA in Lean MetS is not different from Obese MetS.

An approach to estimate bidirectional mediation effects with application to body mass index and fasting glucose

Obesity and type 2 diabetes are major public health issues with known interdependence. Genetic variants have been associated with obesity, type 2 diabetes, or both; thus, we hypothesize that some single nucleotide polymorphisms (SNPs) associated with both conditions may be mediated through obesity to affect type 2 diabetes or vice versa. We propose a framework for bidirectional mediation analyses. Simulations show that this approach accurately estimates the parameters, whether the mediation is unidirectional or bidirectional. In many scenarios, when the mediator is regressed on the initial variable and the outcome is regressed on the mediator and the initial variable, the resulting residuals are correlated because of other unmeasured covariates not in the model. We show that the proposed model provides accurate estimates in this scenario, too. We applied the proposed approach to investigate the mediating effects of SNPs associated with type 2 diabetes and obesity using genetic data from the Multi-Ethnic Study of Atherosclerosis cohort. Specifically, we used body mass index (BMI) as a measure for obesity and fasting glucose as a measure for type 2 diabetes. We evaluated the top 6 SNPs associated with both BMI and fasting glucose. Two SNPs (rs3752355 and rs6087982) had indirect effects on BMI mediated through fasting glucose [0.2677; 95% confidence interval (CI) (0.0007, 0.6548) and 0.3301; 95% CI (0.0881, 0.8544), respectively]. The remaining four SNPs (rs7969190, rs4869710, rs10201400, and rs12421620) directly affect BMI and fasting glucose without mediating effects.

Association between vitamin D deficiency and lipid and non-lipid markers of cardiovascular diseases in the middle east region

BACKGROUND

Previous studies have associated vitamin D deficiency with cardiovascular disease (CVD) markers. The underlying mechanism remains elusive. Lipid and non-lipid markers of CVD and their relationship to vitamin D deficiency have not been assessed simultaneously.

OBJECTIVE

To measure the association between vitamin D deficiency and non-lipid markers of CVD after adjustment of lipid markers.

METHODS

This cross-sectional study used the following biological data, which was routinely collected in a general hospital laboratory database between 2011 and 2016: 25OH vitamin D [25(OH)D], creatinine, CKD-EPI eGFR (eGFR), fasting blood glucose (FPG), glycated hemoglobin (HbA1c), uric acid, γ-glutamyl transferase (γGT), C-reactive protein (CRP), total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and a surrogate for CVD. Crude odds ratios (ORs) and ORs adjusted for lipid profile, gender and age using separate logistic regression models were derived.

RESULTS

A total of 8658 subjects were included. Half had 25(OH)D < 20 ng/mL. 25(OH)D was associated with increased odds of CRP, eGFR, increased uric acid, γGT, FPG, HbA1c, male gender, CV status, and abnormal lipid markers. After adjustment for lipid markers, age, and gender, vitamin D deficiency was associated with increased odds of CRP, eGFR, γGT, FPG, HbA1c, and the surrogate for CVD.

CONCLUSIONS

In this exploratory analysis, the first of its kind in the MENA region, vitamin D deficiency was associated with abnormal lipid markers, non-lipid markers of CVD, male gender, lower eGFR, and a surrogate variable for CVD. The association between vitamin D deficiency and non-lipid markers of CVD persisted after adjustment for lipid markers, age, and gender.

The association between serum uric acid and glaucoma severity in primary angle closure glaucoma: a retrospective case-control study

Uric acid (UA) is a major antioxidant molecule and has been hypothesized to have a protective effect on the central nervous system against oxidative damage. We prospectively investigated the serum concentration of UA in primary angle closure glaucoma (PACG), and explored the association between serum concentration of UA and the severity of PACG. Using a retrospective case-control study design, 886 PACG subjects and 994 control subjects who attended the Eye & ENT Hospital of Fudan University, were eligible for this study. Glaucoma severity was classified as mild (MD ≤ 6.00 dB), moderate (12 dB ≥ MD > 6 dB) and severe (MD > 12 dB) based on the MD (mean deviation). The levels of UA were significantly lower (p = 0.025) in PACG (0.286 ± 0.082 mmol/l) compared with control (0.295 ± 0.085 mmol/l). The mean serum UA levels were lowest in the severe group (0.281 ± 0.074 mmol/l) followed by moderate (0.282 ± 0.080 mmol/l) and mild (0.297 ± 0.090 mmol/l) with significant differences among the three groups (p = 0.032). In multivariate regression analysis, there was a significant negative correlation between UA level and vertical cup-disc ratio (B = −0.165, p = 0.035). Significantly lower serum UA concentration in PACG and its negative association with disease severity presented it as an important candidate in reaction to oxidative stress in glaucoma pathogenesis.