Coexistence of hyper-uricaemia and low urinary uric acid excretion further increases risk of chronic kidney disease in type 2 diabetes

Asymptomatic Hyperuricemia: A Nephro-Rheumatological Perspective

Hyperuricemia (HU) is a common disorder associated with gout, kidney injury, and high cardiovascular risk. However, whether high serum uric acid (sUA) is a causative factor or just comorbidity remains unclear. When asked if asymptomatic hyperuricemic patients need treatment, even artificial intelligence in the form of the GPT chat provides an ambivalent answer and refers us to a healthcare provider. We believe that such discrepancies stem from an incomplete understanding of the role that uric acid (UA) plays inside and outside the cell. With the rapid development of genomics, proteomics, immunology, and novel biomarkers, we are armed with new data to help us better understand the weight of inborn and environmental factors on an individual's UA concentrations. This review sums up the latest progress that has been made in the field of asymptomatic HU, compares the results presented by various research teams, and indicates new directions that emerge for future studies.

High-normal unconjugated bilirubin is associated with decreased risk of chronic kidney disease in type 2 diabetes: A real-world study

OBJECTIVE

To investigate the association between serum unconjugated bilirubin (UCB) within normal limits and chronic kidney disease (CKD) in T2DM patients.

METHOD

This cross-sectional, real-world study was performed in 8661 hospitalised T2DM patients. The subjects were stratified into quintiles based on serum UCB levels. The clinical characteristics and CKD prevalence were compared among the UCB quantile groups. The associations of serum UCB levels and quintiles with CKD were also analysed by binary logistic regression.

RESULTS

After controlling for age, sex, and diabetes duration (DD), the CKD prevalence (20.4%, 12.2%, 10.6%, 8.3%, and 6.4% for the first, second, third, fourth, and fifth quintiles, respectively, p < 0.001 for trend) was significantly decreased across the serum UCB quintiles. The fully adjusted regression model showed negative associations of serum UCB levels (OR: 0.660, 95% CI: 0.585-0.744; p < 0.001 for trend) and quintiles (p < 0.001) with the presence of CKD. Compared with the subjects in the lowest UCB quintile, the risk of CKD decreased by 36.2%, 54.3%, 53.8%, and 62.1%, respectively, in those from the second to the highest UCB quintile. Additionally, C-reactive protein (CRP) levels were significantly higher in the subjects with CKD than in those without CKD (p < 0.001), and significantly decreased across the UCB quintiles (p < 0.001 for trend).

CONCLUSIONS

Serum UCB levels within the normal range were significantly and negatively linked to CKD in T2DM patients. High-normal UCB may be an independent protective factor for CKD by its antioxidant and the following anti-inflammatory activities through its signalling activity, which was indicated by clearly decreased CRP levels across the UCB quintiles.

Effects of sodium-glucose cotransporter 2 inhibitors on renal risk factors in patients with abnormal glucose metabolism: a meta-analysis of randomized controlled trials

AIMS

Several trials have assessed the antihyperglycemic effects of sodium-glucose cotransporter 2 inhibitors (SGLT2Is) in patients with type 2 diabetes mellitus (T2DM). We conducted a quantitative analysis to assess the effects of SGLT2Is on renal risk factors in patients with abnormal glucose metabolism.

MATERIALS AND METHODS

Randomized controlled trials (RCTs) were identified by searching the PubMed, Embase, Scopus, and Web of Science databases published before September 30, 2022. The intervention group received SGLT2Is as monotherapy or add-on treatment, and the control group received placebos, standard care, or active control. Risk of bias assessment was performed using the Cochrane risk of bias assessment tool. Meta-analysis was performed on studies with abnormal glucose metabolism populations and studies using the weighted mean differences (WMDs) as the measure of the effect size. Clinical trials providing changes in serum uric acid (SUA) were included. The mean change of SUA, glycated hemoglobin (HbA1c), body mass index (BMI), and estimated glomerular filtration rate (eGFR) were calculated.

RESULTS

After a literature search and detailed evaluation, a total of 11 RCTs were included for quantitative analysis to analyze the differences between the SGLT2I group and the control group. The results showed that SGLT2I significantly reduced SUA (MD =  -0.56, 95% CI =  -0.66 ~ -0.46, I² = 0%, P < 0.00001), HbA1c (MD =  -0.20, 95% CI =  -0.26 ~ -0.13, I² = 0%, P < 0.00001), and BMI (MD =  -1.19, 95% CI =  -1.84 ~ -0.55, I² = 0%, P = 0.0003). There was no significant difference in the reduction of eGFR observed in the SGLT2I group (MD =  -1.60, 95% CI =  -3.82 ~ 0.63, I² = 13%, P = 0.16).

CONCLUSIONS

These results showed that the SGLT2I group caused greater reductions in SUA, HbA1c, and BMI but had no effect on eGFR. These data suggested that SGLT2Is may have numerous potentially beneficial clinical effects in patients with abnormal glucose metabolism. However, these results need to be consolidated by further studies.

The perirenal fat thickness was independently associated with serum uric acid level in patients with type 2 diabetes mellitus

BACKGROUND

Obesity is an important risk factor for hyperuricemia. We aimed to explore the relationship between perirenal fat thickness (PrFT) and paranephric fat thickness (PnFT) and serum uric acid (SUA) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a cross-sectional study involving 257 patients with T2DM recruited from Beijing Luhe Hospital from September 2019 to May 2020. The basic and clinical information such as age, gender, duration of diabetes was collected through the medical records. All patients underwent a physical examination including height, weight, waist circumference, hip circumference, systolic blood pressures and diastolic blood pressure. The venous blood and urine samples were collected to measure SUA, fasting blood glucose, total cholesterol, triglyceride, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, serum creatinine, blood urea nitrogen and glycosylated hemoglobin. PrFT and PnFT were measured via ultrasonography. Pearson correlation test and linear regression analysis were used to analyze the association between PrFT and PnFT and SUA.

RESULTS

We found that PrFT and PnFT increased according to the tertiles of SUA level (P = 0.001 and P = 0.009, respectively). In addition, the PrFT and PnFT were positively associated with SUA level (r = 0.25, P < 0.001, r = 0.23, P < 0.001, respectively). Moreover, this association was stronger in males, non-obesity patients and patients with normal renal function. In the multivariate analysis, the PrFT was independently associated with SUA level after adjusting confounding factors.

CONCLUSIONS

The PrFT was independently associated with SUA level in patients with T2DM.

Management of Hyperuricemia in Patients with Chronic Kidney Disease: a Focus on Renal Protection

PURPOSE OF REVIEW

In chronic kidney disease (CKD), plasma uric acid levels are increased because of the decrease in glomerular filtration rate. However, in addition to CKD, hyperuricemia is frequently associated with a number of other conditions such as hypertension, type 2 diabetes, obesity, and heart failure, overweight, and cardiovascular disease.

RECENT FINDINGS

It is now becoming increasingly clear that, in many clinical conditions, elevated levels of uric acid have a much greater role beyond just causing gout. The present review will summarize current knowledge on the relation between hyperuricemia, CKD, and existing comorbidities, as well as the mechanisms of uric acid-related renal damage. In addition, the role and evidence for urate-lowering therapy in prevention and cardiovascular protection in CKD patients is discussed with a focus on allopurinol and febuxostat. To date, several clinical studies have provided evidence that urate-lowering therapy may help to prevent and delay the decline of renal function in patients with CKD. Use of a xanthine oxidase inhibitor should be considered in patients who are at high renal risk and/or with declining renal function in the presence of hyperuricemia with and without deposition, although additional studies are warranted to define treatment targets. Notwithstanding, the possibility to delay deterioration of renal function in patients with CKD merits consideration.

Efficacy of different urinary uric acid indicators in patients with chronic kidney disease

Background

Mounting studies have shown that hyperuricemia is related to kidney diseases through multiple ways. However, the application of urinary uric acid indicators in patients with reduced renal function is not clear. In this study, we aim to determine the effects of renal function on various indicators reflecting uric acid levels in patients with chronic kidney disease (CKD).

Methods

Anthropometric and biochemical examinations were performed in 625 patients with CKD recruited from Dept of Nephrology of Huadong hospital affiliated to Fudan University. Multiple regression analyses were used to study correlations of the estimated glomerular filtration rate (eGFR) with serum uric acid (SUA) and renal handling of uric acid. For further study, smooth curve plots and threshold effect analyses were applied to clarify associations between renal function and uric acid levels.

Results

The nonlinear relationships were observed between eGFR and urinary uric acid indicators. The obvious inflection points were observed in smooth curve fitting of eGFR and fractional excretion of uric acid (FEur), excretion of uric acid per volume of glomerular filtration (EurGF). In subsequent analyses where levels of eGFR< 15 mL/min/1.73m² were dichotomized (CKD5a/CKD5b), patients in the CKD5a showed higher levels of FEur and EurGF while lower levels of urinary uric acid excretion (UUA), clearance of uric acid (Cur) and glomerular filtration load of uric acid (FLur) compared with CKD5b group (all P < 0.05). And there was no significant difference of SUA levels between two groups. On the other hand, when eGFR< 109.9 ml/min/1.73 m² and 89.1 ml/min/1.73 m², the resultant curves exhibited approximately linear associations of eGFR with Cur and FLur respectively.

Conclusion

FEur and EurGF showed significantly compensatory increases with decreased renal function. And extra-renal uric acid excretion may play a compensatory role in patients with severe renal impairment to maintain SUA levels. Moreover, Cur and FLur may be more reliable indicators of classification for hyperuricemia in CKD patients.