To treat or not to treat asymptomatic hyperuricemia in chronic kidney disease

Hyperuricemia, a Non-Independent Component of Metabolic Syndrome, Only Predicts Renal Outcome in Chronic Kidney Disease Patients without Metabolic Syndrome or Diabetes

Uric acid (UA) is elevated in metabolic syndrome (MS) and diabetes (DM). UA is associated with central obesity and blood glucose and is proposed as a criterion of MS. Previous reports showed that UA could predict renal outcome in CKD. However, recent clinical trials did not demonstrate the benefits of urate-lowering agents (ULA) for renal outcome. Whether the prognostic value of UA for renal outcome is independent of MS or secondary to MS in CKD patients is unknown. Our study included 2500 CKD stage 1−4 Asian patients divided by UA tertiles and MS/DM. In linear regression, UA was associated with obesity, C-reactive protein, and renal function. In Cox regression, high UA was associated with worse renal outcome in non-MS/DM, but not in MS/DM: hazard ratio (95% confidence interval) of UA tertile 3 was 3.86 (1.87−7.97) in non-MS/DM and 1.00 (0.77−1.30) in MS/DM (p for interaction < 0.05). MS was associated with worse renal outcome, but redefined MS (including hyperuricemia as the 6th criteria) was not. In conclusion, hyperuricemia is associated with worse renal outcome in non-MS/DM and is not an independent component of MS in CKD stage 1−4 patients. Hyperuricemia secondary to MS could not predict renal outcome.

High-level uric acid in asymptomatic hyperuricemia could be an isolated risk factor of cardio-cerebrovascular diseases: A prospective cohort study

BACKGROUND AND AIMS

Whether the asymptomatic hyperuricemia (AH) raise the cardiovascular disease risk with or without hyperuricemia-related comorbidities still remains contentious. Our study was aimed to quantitatively access the incidence risk of coronary heart disease (CHD) and stroke associated with AH.

METHODS AND RESULTS

In this prospective cohort study, multivariate-adjusted Cox regression models were applied to evaluate the risk of cardiovascular disease (CVD). Baseline serum uric acid beyond normouricemia (357 mmol/L) was quarterly stratified based on the distribution of healthy populations without CVD onset. 1062 CVD first-attack cases were collected among the 29,974 study population (age range: 18-91, mean age: 47.2 ± 13.9 years-old) with a mean follow-up duration of 5.78 ± 0.83 years. The AH showed overall non-association with the CVD incident. However, significantly increased adjusted hazard ratio (HR) of CVD with 95% confidence interval (CI) were observed when the fourth quartile compared with normouricemia stratum in the total cohort population (CHD: 1.42, 1.21-1.68; stroke: 1.27, 1.06-1.41), male (CHD: 1.26, 1.12-1.55), female (CHD: 1.34, 1.04-2.02; stroke: 2.06, 1.13-3.77) and aged over 50 years-old population. Meanwhile, the age-standardized incidence rate of CVD in the fourth quartile was 2-3 times higher than the normouricemia population. After excluded 14,464 baseline population with diabetes, dyslipidemia, and hypertension, consistent results were also observed in the AH population in absence of comorbidities (CHD: 1.51, 1.22-2.25; stroke: 1.68, 1.13-2.39).

CONCLUSION

Asymptomatic hyperuricemia patients exposed to a higher level of uric acid (>=428 mmol/L) could significantly increase the incidence risk of CHD and stroke, with or without hyperuricemia-related comorbidities.

Association between serum uric acid and left ventricular hypertrophy/left ventricular diastolic dysfunction in patients with chronic kidney disease

Background

The level of serum uric acid (SUA) has been reported to be associated with left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD). However, this association remains unclear in patients with chronic kidney disease (CKD).

Methods

A total of 1025 patients with pre-dialysis CKD with preserved left ventricular systolic function were enrolled in this cross-sectional study. The LVH and LVDD were assessed using two-dimensional echocardiography and tissue Doppler imaging. The associations of LVH/LVDD with clinical and laboratory variables were investigated using univariable and multivariable logistic regression analyses.

Results

In a multivariable analysis, the SUA level was an independent predictor of LVH (odds ratio [OR]: 1.40, 95% confidence interval [CI]: 1.31–1.50, P < 0.001). In addition, patient age, systolic blood pressure, intact parathyroid hormone levels, and left atrial volume index levels were independent predictors of LVH. The SUA level was also an independent predictor of LVDD (OR: 1.93, 95% CI: 1.53–2.43, P < 0.001). Furthermore, systolic blood pressure and left atrial volume index levels were an independent predictor of LVDD. Receiver-operating characteristic curve analysis showed that the best cutoff values of SUA levels for identifying LVH and LVDD were ≥ 7.5 mg/dL and ≥ 6.3 mg/dL, respectively.

Conclusion

The SUA level was an independent predictor of LVD and LVDD in patients with CKD, suggesting that SUA could be a biomarker for LVH and LVDD.

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.

HLA-B*58: 01 association in allopurinol-induced severe cutaneous adverse reactions: the implication of ethnicity and clinical phenotypes in multiethnic Malaysia

OBJECTIVE

The association between human leukocyte antigen (HLA)-B*58:01 and risk of allopurinol-induced severe cutaneous adverse reactions (AIS) was observed across different populations. We explore the association between HLA-B*58:01 and AIS risk in multiethnic Malaysian population. The HLA-B*58:01 risk for different AIS clinical phenotypes and ethnicity was determined.

METHODS

We performed a case-control association study by genotyping the HLA-B alleles of 55 patients with AIS [11 toxic epidermal necrolysis (TEN), 21 Steven Johnson syndrome (SJS) 22 drug reaction wit eosinophilia and systemic symptoms (DRESS) and one acute generalized exanthematous pustulosis (AGEP)] and 42 allopurinol-tolerant controls (ATC).

RESULTS

HLA-B*58:01 was positive in 89.1 and 14.3% of the AIS and ATC study groups [odds ratio (OR) = 49.0, 95% confidence interval (CI) = 14.6-164.4, P < 0.0001)], respectively. Our data showed that 93.8% of the AIS-SJS/TEN patients and 86.4% of the AIS-DRESS patients were HLA-B*58:01 positive (AIS-SJS/TEN, OR = 90, 95% CI = 16.9-470.1, P < 0.0001 and AIS-DRESS OR = 38, 95% CI = 8.5-169.2, P < 0.0001). Stratification by ethnicity and clinical phenotypes revealed a significant increased risk between HLA-B*58:01 and Chinese-AIS patients (OR = 137.5, 95% CI = 11.3-1680.2, P < 0.0001), in particular Chinese patients with AIS-SJS/TEN phenotype (100% HLA-B*58:01 positive). HLA-B*58:01 was positive in 90.9% Chinese AIS-DRESS (P < 0.0001). Highly significant associations of HLA-B*58:01 were observed in Malay AIS-SJS/TEN (OR = 78, 95% CI = 9.8-619.9, P < 0.0001) and Malay AIS-DRESS (OR = 54, 95% CI = 6.6-442.9, P < 0.0001). Although the number of Indian-AIS patients was relatively small (n = 2), both were HLA-B*58:01 positive.

CONCLUSION

Our data suggest strong associations between HLA-B*58:01 and AIS in Malaysian population with Chinese and Malays ethnicity. The strong association was also observed in three different clinical phenotypes of AIS, mainly the AIS-SJS/TEN.

Uric acid and inflammation in kidney disease

Asymptomatic hyperuricemia is frequently observed in patients with kidney disease. Although a substantial number of epidemiologic studies have suggested that an elevated uric acid level plays a causative role in the development and progression of kidney disease, whether hyperuricemia is simply a result of decreased renal excretion of uric acid or is a contributor to kidney disease remains a matter of debate. Over the last two decades, multiple experimental studies have expanded the knowledge of the biological effects of uric acid beyond its role in gout. In particular, uric acid induces immune system activation and alters the characteristics of resident kidney cells, such as tubular epithelial cells, endothelial cells, and vascular smooth muscle cells, toward a proinflammatory and profibrotic state. These findings have led to an increased awareness of uric acid as a potential and modifiable risk factor in kidney disease. Here, we discuss the effects of uric acid on the immune system and subsequently review the effects of uric acid on the kidneys mainly in the context of inflammation.