Relationship between serum uric acid concentration and insulin resistance and metabolic syndrome

Serum Uric Acid as an Independent Predictor of Early Death After Acute Stroke

BACKGROUND

The prognostic significance of uric acid (UA) levels in acute stroke is unclear, so the objective of this study was to determine the association between levels of serum UA (SUA) and mortality in acute stroke.

METHODS AND RESULTS

Consecutive patients (n=435) presenting with ischemic stroke and intracerebral hemorrhage were included in the study. The length of stay in hospital and the occurrence of death were recorded. On univariate analysis, the occurrence of death was associated with older age, smoking, presence of congestive heart failure or atrial fibrillation, absence of hyperlipidemia, and intracerebral hemorrhage as the index event. Furthermore, glucose, urea, creatinine and SUA at admission were significantly higher in patients who died, whereas total and high-density-lipoprotein cholesterol were significantly lower. On multiple logistic regression analysis, the independent relationship between higher SUA levels and death was confirmed (odds ratio (OR), 1.37; 95%confidence interval (CI), 1.13-1.67; p=0.001). The only other variables independently associated with the occurrence of death were urea concentration and presence of atrial fibrillation. If urate was >7.8 mg/dl (0.47 mmol/L), then there would be a high probability of early death (87%).

CONCLUSIONS

Elevated levels of SUA are independently associated with an increased risk of early death in acute stroke.

Hyperuricemia and incidence of hypertension among men without metabolic syndrome

The aim of this project was to study the risk of developing hypertension over a 6-year follow-up in normotensive men with baseline hyperuricemia (serum uric acid >7.0 mg/dL) but without diabetes/glucose intolerance or metabolic syndrome. We analyzed the data on men without metabolic syndrome or hypertension at baseline from the Multiple Risk Factor Intervention Trial. These men (n=3073; age: 35 to 57 years) were followed for an average of 6 years by annual examinations. Follow-up blood pressure among those with baseline was consistently higher than among those with normal serum uric acid concentration. We used Cox regression models for adjustment for the effects of serum creatinine, body mass index, age, blood pressure, proteinuria, serum cholesterol and triglycerides, alcohol and tobacco use, risk factor interventions, and use of diuretics. In these models, normotensive men with baseline hyperuricemia had an 80% excess risk for incident hypertension (hazard ratio: 1.81; 95% CI: 1.59 to 2.07) compared with those who did not. Each unit increase in serum uric acid was associated with a 9% increase in the risk for incident hypertension (hazard ratio: 1.09; 95% CI: 1.02 to 1.17). We conclude that the hyperuricemia-hypertension risk relationship is present among normotensive middle-aged men without diabetes/glucose intolerance or metabolic syndrome.

J-shaped mortality relationship for uric acid in CKD

BACKGROUND

Hyperuricemia is a common feature in patients with chronic kidney disease (CKD). Hyperuricemia has been associated with increased cardiovascular mortality in the general population, but less is known about this association in patients with CKD.

METHODS

To explore possible associations of serum uric acid with all-cause mortality and comorbidity in patients with CKD, we studied 294 incident patients with CKD stage 5 (185 men; age, 53 +/- 12 years) starting renal replacement therapy with a median glomerular filtration rate of 6.4 mL/min/1.73 m(2) (0.11 mL/s/1.73 m(2); range, 0.8 to 14.3 mL/min/1.73 m(2) [0.01 to 0.24 mL/s/1.73 m(2)]). Survival was determined from the day of examination and during a mean follow-up period of 27 months (range, 3 to 72 months); 94 patients died. Patients were divided into 3 groups based on serum uric acid levels (low quintile, 3 middle quintiles, and high quintile).

RESULTS

In a nonadjusted analysis, patients in the high quintile, followed by patients in the low quintile, had greater all-cause mortality compared with patients in the 3 middle quintiles (log-rank test chi-square, 6.8; P = 0.03). After adjusting for age, sex, glomerular filtration rate, cholesterol level, phosphate level, C-reactive protein level, cardiovascular disease, diabetes mellitus, diuretics, and allopurinol treatment, the association showed a "J-shaped" association with hazard ratios of 1.96 (confidence interval, 1.10 to 3.48; P = 0.02) for the high quintile and 1.42 (confidence interval, 0.76 to 2.66; P = not significant) for the low quintile. Moreover, uric acid levels correlated positively with levels of triglycerides, phosphate, C-reactive protein, and intracellular adhesion molecule 1 and negatively with levels of calcium, high-density lipoprotein cholesterol, and apolipoprotein A.

CONCLUSION

Serum uric acid levels showed a J-shaped association with all-cause mortality, with the lowest risk in the 3 middle quintiles. Moreover, uric acid level was associated with calcium/phosphate metabolism, dyslipidemia, and inflammation.

Prevalence of hyperuricemia and its relationship with metabolic syndrome in Thai adults receiving annual health exams

BACKGROUND

Associations between hyperuricemia, metabolic syndrome, cardiovascular disease and diabetes have been reported. Limited information, however, is available concerning the prevalence and correlates of hyperuricemia among Thai men and women. We sought to estimate the prevalence of hyperuricemia among a population of patients receiving annual health exams and to evaluate its relationship with metabolic syndrome (MetS).

METHODS

We conducted a cross-sectional study of 1,381 patients (376 men and 1,005 women) who first participated in annual health examinations at the Preventive Medicine Clinic of the King Chulalongkorn Memorial Hospital in Bangkok, Thailand during the period July 1999 through February 2000. Hyperuricemia was defined as >7.0 mg/dL in men and >6.0 mg/dL in women. MetS was defined using the modified ATP III criteria.

RESULTS

The overall prevalence of the hyperuricemia was 10.6%. The condition was more common in men than in women (18.4 vs. 7.8%). Among women, serum uric acid was statistically significantly correlated with body mass index (BMI), systolic and diastolic blood pressure, high-density lipoprotein-cholesterol, triglyceride and fasting plasma glucose (all p <0.05). Men with serum uric acid concentrations >6.7 mg/dL (upper quartile) had a 3.91-fold increased in risk of MetS (95% CI:1.36-11.23), as compared with those who had concentrations <5.1 mg/dL (lowest quartile). Among women, the risk of MetS increased at least 2-fold for concentration of serum uric acid concentrations >4.0 mg/dL (p for trend <0.001).

CONCLUSIONS

Hyperuricemia is prevalent among Thai men and women receiving routine health exams. Additionally, serum uric acid is positively associated with MetS.

The association between serum uric acid level and long-term incidence of hypertension: Population-based cohort study

Increasing experimental evidence, including recently developed animal models support a causal role for uric acid in the development of hypertension. However, it is not clear whether serum uric acid levels are independently associated with the long-term incidence of hypertension. We examined the association between serum uric acid levels and 10-year incidence of hypertension in a population-based cohort study based in Beaver Dam city and township, Wisconsin, US. We studied 2520 hypertension-free individuals (56.3% women, age: 43-84 years, 98% Caucasian) at the baseline examination (1988-1990). The main outcome of interest was hypertension (systolic blood pressure (BP) of 140 mm Hg or higher, diastolic BP 90 mm Hg or higher, or combination of self-reported high BP diagnosis and use of antihypertensive medications) incidence over 10 years among baseline normotensive individuals. Nine hundred and fifty-six individuals developed hypertension over a 10-year follow-up period. The relative risk (RR) (95% confidence intervals (CI)) of incident hypertension increased in a dose-dependent manner (P-trend < 0.05 in all models) with increasing uric acid quartiles. Multivariable RR (95% CI) comparing the highest quartile of serum uric acid (> or =390 micromol/l) to the lowest quartile (< or =260 micromol/l) was 1.65 (1.41-1.93). This association persisted in subgroup analyses by categories of smoking, alcohol intake, body mass index, baseline blood pressure and estimated glomerular filtration rate (GFR). In conclusion, increasing quartiles of serum uric acid was associated with 10-year incidence of hypertension independent of smoking, alcohol intake and baseline kidney function suggesting an independent positive association between serum uric acid levels and hypertension development among community-dwelling older adults.

Elevated serum uric acid levels in metabolic syndrome: an active component or an innocent bystander?

Elevated serum uric acid (SUA) levels are commonly seen in patients with the metabolic syndrome (MetS). Several mechanisms, both direct and indirect, connect the increased SUA levels with the established diagnostic criteria of MetS. It is possible that the increased cardiovascular disease risk associated with the MetS is partially attributed to elevated circulating SUA concentration. Several drugs used in the treatment of MetS may alter SUA levels. Thus, lifestyle measures together with the judicious selection of drugs for the treatment of hypertension, dyslipidemia, and insulin resistance associated with MetS may result in a reduction of SUA levels and possibly cardiovascular disease risk. This review summarizes the pathophysiologic association between SUA and MetS and focuses on the prevention of hyperuricemia and its cardiovascular consequences.

Prevalence and risk factors of nonalcoholic fatty liver disease in an adult population of taiwan: metabolic significance of nonalcoholic fatty liver disease in nonobese adults

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rarely reported in Taiwan.

GOALS

To determine the prevalence and risk factors of NAFLD in an adult population of Taiwan.

STUDY

The cross-sectional community study examined 3245 adults in a rural village of Taiwan. The diagnostic criteria for NAFLD included no excessive alcohol intake, no chronic viral hepatitis, no known etiologies of liver disease, and ultrasonography consistent with fatty liver.

RESULTS

The prevalence of NAFLD was 11.5% (372/3245). The risk factors for NAFLD in the general population were male sex [odds ratio (OR), 1.44; 95% confidence interval (CI), 1.09-1.90], elevated alanine aminotransferase (ALT) (OR, 5.66; 95% CI, 3.99-8.01), obesity (OR, 7.21; 95% CI, 5.29-9.84), fasting plasma glucose > or =126 mg/dL (OR, 2.08; 95% CI, 1.41-3.05), total cholesterol > or =240 mg/dL (OR, 1.50; 95% CI, 1.06-2.13), triglyceride > or =150 mg/dL (OR, 1.76; 95% CI, 1.32-2.35), and hyperuricemia (OR, 1.53; 95% CI, 1.16-2.01). Age > or =65 years was inversely related to NAFLD (OR, 0.53; 95% CI, 0.36-0.77). The only NAFLD risk factors among nonobese subjects were age between 40 and 64 years (OR, 2.35; 95% CI, 1.34-4.11, P=0.003), elevated ALT (OR, 15.45; 95% CI, 8.21-29.09, P<0.001), and triglyceride > or =150 mg/dL (OR, 2.48; 95% CI, 1.42-4.32, P=0.001). In subjects with NAFLD, the prevalence of elevated ALT in the presence of each metabolic risk factor, such as obesity, fasting plasma glucose > or =126 mg/dL, total cholesterol > or =240 mg/dL, triglyceride > or =150 mg/dL, and hyperuricemia, did not differ from that of subjects with normal ALT levels.

CONCLUSIONS

NAFLD is closely associated with elevated ALT, obesity, diabetes mellitus, hypercholesterolemia, hypertriglyceridemia, and hyperuricemia. Among the metabolic disorders, only hypertriglyceridemia was related to NAFLD in nonobese subjects. Serum ALT level was not a good predictor of metabolic significance in subjects with NAFLD.

Crystal-induced arthropathies: recent investigative advances

PURPOSE OF REVIEW

To highlight recent investigations that have stimulated renewed interest in crystal-induced arthropathies.

RECENT FINDINGS

Specific diet-related and alcohol-related risks for gout have been clarified, and alternative urate-lowering treatments likely to benefit patients with difficult-to-treat gout are in development. Progress toward understanding mechanisms underlying the renal deficits defining most cases of gout includes characterization of a urate-specific renal tubule transporter explaining many aspects of renal uric acid handling and identification of mutations in the UMOD gene, resulting in altered uromodulin protein in the gout-associated disorders familial juvenile hyperuricemic nephropathy and medullary cystic kidney disease type 2. A genetic marker associated with the risk for severe allopurinol toxicity has been reported. Hyperuricemia and gout are increasing in incidence, as is complicated gout, especially among the elderly and patients with cardiovascular and renal comorbidities, organ transplants, or complex concomitant medication regimens. Asymptomatic hyperuricemia is clearly associated with hypertension, chronic kidney disease, cardiovascular disease, and the insulin resistance syndrome, and the pathogenetic significance of these associations is under intensive study. Mutation in the ANKH gene has been found among some patients with sporadic as well as familial calcium pyrophosphate deposition disease.

SUMMARY

The results of these clinical, epidemiologic, experimental, and therapeutic investigations presage advances in the management of crystal-induced arthropathies.

Vanadyl sulfate administration protects the streptozotocin-induced oxidative damage to brain tissue in rats

Diabetes mellitus manifests itself in a wide variety of complications and the symptoms of the disease are multifactorial. The present study was carried out to investigate the effects of vanadyl sulfate on biochemical parameters, enzyme activities and brain lipid peroxidation, glutathione and nonenzymatic glycosylation of normal- and streptozotocin-diabetic rats. Streptozotocin (STZ) was administered as a single dose (65 mg/kg) to induce diabetes. A dose of 100 mg/kg vanadyl sulfate was orally administered daily to STZ-diabetic and normal rats, separately until the end of the experiment, at day 60. In STZ-diabetic group, blood glucose, serum sialic and uric acid levels, serum catalase (CAT) and lactate dehydrogenase (LDH) activities, brain lipid peroxidation (LPO) and nonenzymatic glycosylation (NEG) increased, while brain glutathione (GSH) level and body weight decreased. In the diabetic group given vanadyl sulfate, blood glucose, serum sialic and uric acid levels, serum CAT and LDH activities and brain LPO and NEG levels decreased, but brain GSH and body weight increased. The present study showed that vanadyl sulfate exerted antioxidant effects and consequently may prevent brain damage caused by streptozotocin-induced diabetes.

Polymorphism of methylenetetrahydrofolate reductase gene (C677T MTHFR) is not a confounding factor of the relationship between serum uric acid level and the prevalence of hypertension in Japanese men

BACKGROUND

The association between serum uric acid (UA) and the prevalence of hypertension, and the relationship between methylenetetrahydrofolate reductase (MTHFR) polymorphism and hypertension remains unclear. The aim of the present study was to investigate whether the C677T MTHFR mutation genotype (VV) is independently associated with the prevalence of hypertension or blood pressure (BP), and examined any interaction of MTHFR and UA with BP.

METHODS AND RESULTS

Participants were randomly selected from all residents (aged 40-69 years) in a rural county of Japan, and the data for the men (n=335) were analyzed. ;Hypertension' was defined as systolic BP >or=140 and/or diastolic BP >or=90 mmHg and/or being administered antihypertensive medication. Serum UA level was independently associated with the prevalence of hypertension (odds ratio (95% confidence interval) =2.7 (1.2-5.9), p=0.047) for the highest tertile of serum UA (>or=398.5 micromol/L (6.7 mg/dl)) vs that of the lowest tertile (<321.2 micromol/L (5.4 mg/dl)), but the MTHFR mutation was not independently associated with prevalence of hypertension or BP. No interaction of the MTHFR mutation and serum UA with BP was found.

CONCLUSIONS

The mutation of C677T MTHFR was not independently associated with the prevalence of hypertension or BP levels although serum UA was. Furthermore, the relationship between serum UA and BP was not modulated by the MTHFR mutation in Japanese men.

Gender-Related Association of Serum Uric Acid and Left Ventricular Hypertrophy in Hypertension

BACKGROUND

The aim of the present study was to determine whether sex differences contribute to the association of serum uric acid and left ventricular hypertrophy in individuals with hypertension.

METHODS AND RESULTS

Seventy participants with essential hypertension (34 men, 36 women; 54.4 +/- 1.6 years old) were enrolled to undergo echocardiography to calculate the left ventricular mass index (LVMI). Twenty-four-hour ambulatory blood pressure monitoring was done to assess blood pressure level precisely. The LVMI was significantly correlated with serum uric acid (r = 0.295, p = 0.013) in all participants. After controlling for factors such as age, sex, mean 24-h systolic blood pressure, creatinine clearance, and duration of hypertension, serum uric acid was still found to be significantly and independently associated with LVMI. Because serum uric acid was significantly higher in men than in women (6.8 +/- 0.3 and 5.1 +/- 0.2 mg/dl, respectively), subsequent analysis was performed by gender. Multiple regression analysis revealed that the LVMI was significantly and independently associated with serum uric acid in women, but not in men.

CONCLUSIONS

The potential effect of uric acid on LV hypertrophy is more pronounced in female than in males with essential hypertension.