Effect of insulin on uric acid excretion in humans

Relation between serum uric acid and carotid intima-media thickness in healthy postmenopausal women

OBJECTIVE

Serum uric acid (SUA) is associated with cardiovascular disease (CVD). However it is still disputed whether the relationship is mediated by other risk factors such as obesity, dyslipidaemia, hypertension and insulin resistance. We explored the association of the uric acid level with carotid intima-media thickness (IMT), a well known marker of CVD, in postmenopausal healthy women.

METHODS

We consecutively enrolled postmenopausal women undergoing a screening for health evaluation. After an accurate clinical examination, and a biochemical evaluation, the enrolled subjects underwent B mode ultrasonography to assess common carotid intima media thickness.

RESULTS

Among 234 women aged 45-70 years, the uric acid level is associated with carotid IMT independently of other prognostic factors (p=0.03). In particular, women in the highest tertiles of uric acid level have a greater IMT than women in the lowest tertile (p=0.007).

CONCLUSIONS

Independently of other cardiovascular risk factors, SUA levels are associated with carotid IMT even in subjects without the metabolic syndrome. This confirms and expands the role of uric acid in the determinism of CVD. Prospective trials would be useful to evaluate interventions aimed at lowering the uric acid level.

Manifestations of metabolic syndrome associated with male gout in different age strata

We examined the components of metabolic syndrome associated with gout in different age strata by a large-scale case-controlled study. Totally, 12,179 gouty subjects were divided into three groups according to their ages at first visit: young- (19-44 years), middle- (45-64 years), and old-aged (>or=65 years) groups. Their clinical and laboratory data, as well as the risk of gout by the metabolic syndrome, were analyzed in three age groups and compared with a control population. The numbers of the cases in the young-, middle-, and old-aged groups in the gout population were 4,698, 4,847, and 2,634, respectively. The serum urate level and the percentage of positive family history of gout were the highest in young-aged group and declined with increasing age. When compared with the data of the control population, the incidence of overweight (body mass index, >or=24.2 kg/m(2)) and hypertriglyceridemia (triglyceride, >or=2.26 mmol/l) were significantly higher in the gout population for all age groups. The incidence of type 2 diabetes was significantly higher in the gout as well for all age groups, and the odds ratio was highest in the young-aged group [odds ratio (95% confidence interval), 5.55 (3.05-10.09)]. In all, except for the old-aged groups, the incidence of hypercholesterolemia was significantly higher in the gout than in the control population, whereas the incidence of hypertension was significantly higher in the gout than in the control population only in the old-aged group. Various clinical and laboratory data were suggested to be the risks of gout in different degrees between age strata.

Familial clustering for features of the metabolic syndrome: the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study

OBJECTIVE

Metabolic syndrome-related traits (obesity, glucose intolerance/insulin resistance, dyslipidemia, and hypertension) have been shown to be genetically correlated. It is less clear, however, if the genetic correlation extends to novel risk factors associated with inflammation, impaired fibrinolytic activity, and hyperuricemia. We present a bivariate genetic analysis of MetS-related traits including both traditional and novel risk factors.

RESEARCH DESIGN AND METHODS

Genetic correlations were estimated using a variance components procedure in 1,940 nondiabetic white individuals from 445 families in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study. Twelve MetS-related traits, including BMI, waist circumference, blood pressure, white blood cell count, fasting serum triglycerides, HDL cholesterol, insulin, glucose, plasminogen activator inhibitor-1 antigen, uric acid, and C-reactive protein, were measured and adjusted for covariates, including lifestyle variables.

RESULTS

Significant genetic correlations were detected among BMI, waist circumference, HDL cholesterol, triglycerides, insulin, and plasminogen activator inhibitor-1 antigen and between uric acid and all of the above variables except insulin. C-reactive protein and white blood cell count were genetically correlated with each other, and both showed significant genetic correlations with waist circumference and insulin. Fasting glucose was not significantly genetically correlated with any of the other traits.

CONCLUSIONS

These results suggest that pleiotropic effects of genes or shared family environment contribute to the familial clustering of MetS-related traits.

Contribution of polymorphisms in the apolipoprotein AI-CIII-AIV cluster to hyperlipidaemia in patients with gout

BACKGROUND

Studies have shown that hyperuricaemia is independently related to the insulin resistance syndrome and that polymorphisms of the apolipoprotein AI-CIII-AIV cluster are also related to insulin resistance.

OBJECTIVE

To study the prevalence of polymorphisms of the apolipoprotein AI-CIII-AIV cluster in persons with gout and to determine whether these polymorphisms contribute to the pathophysiology of gout or to altered lipid concentrations.

METHODS

Plasma cholesterol, triglycerides, uric acid, VLDL, LDL, IDL, and HDL triglycerides, cholesterol, and the renal excretion of uric acid were measured in 68 patients with gout with gout and 165 healthy subjects. Polymorphisms were studied by amplification and RFLP in all subjects, using XmnI and MspI in the apolipoprotein AI gene and SstI in the apolipoprotein CIII gene.

RESULTS

The A allele at position -75 bp in the apolipoprotein AI gene was more common in patients with gout than in controls (p = 0.01). Levels of cholesterol, triglycerides, uric acid, basal glycaemia, and HDL cholesterol were higher in the patients (p<0.001). In the patients there was also an interaction between mutations at the two polymorphic loci studied in the apolipoprotein AI gene (p = 0.04). An absence of the mutation at position -75 bp of the apolipoprotein AI gene resulted in increased plasma triglyceride levels.

CONCLUSIONS

Gouty patients have an altered allelic distribution in the apolipoprotein AI-CIII-AIV cluster, which could lead to changes in levels of lipoproteins. This is not caused by a single mutation but rather by a combination of different mutations.

Prevalence of hyperuricemia and relation of serum uric acid with cardiovascular risk factors in a developing country

BACKGROUND

The prevalence of hyperuricemia has rarely been investigated in developing countries. The purpose of the present study was to investigate the prevalence of hyperuricemia and the association between uric acid levels and the various cardiovascular risk factors in a developing country with high average blood pressures (the Seychelles, Indian Ocean, population mainly of African origin).

METHODS

This cross-sectional health examination survey was based on a population random sample from the Seychelles. It included 1011 subjects aged 25 to 64 years. Blood pressure (BP), body mass index (BMI), waist circumference, waist-to-hip ratio, total and HDL cholesterol, serum triglycerides and serum uric acid were measured. Data were analyzed using scatterplot smoothing techniques and gender-specific linear regression models.

RESULTS

The prevalence of a serum uric acid level >420 micromol/L in men was 35.2% and the prevalence of a serum uric acid level >360 micromol/L was 8.7% in women. Serum uric acid was strongly related to serum triglycerides in men as well as in women (r = 0.73 in men and r = 0.59 in women, p < 0.001). Uric acid levels were also significantly associated but to a lesser degree with age, BMI, blood pressure, alcohol and the use of antihypertensive therapy. In a regression model, triglycerides, age, BMI, antihypertensive therapy and alcohol consumption accounted for about 50% (R2) of the serum uric acid variations in men as well as in women.

CONCLUSIONS

This study shows that the prevalence of hyperuricemia can be high in a developing country such as the Seychelles. Besides alcohol consumption and the use of antihypertensive therapy, mainly diuretics, serum uric acid is markedly associated with parameters of the metabolic syndrome, in particular serum triglycerides. Considering the growing incidence of obesity and metabolic syndrome worldwide and the potential link between hyperuricemia and cardiovascular complications, more emphasis should be put on the evolving prevalence of hyperuricemia in developing countries.

Absence of an association between serum uric acid and mortality from cardiovascular disease: NIPPON DATA 80, 1980-1994. National Integrated Projects for Prospective Observation of Non-communicable Diseases and its Trend in the Aged

Although elevated serum uric acid has been associated with an increased risk of cardiovascular disease, its importance as a risk factor is still controversial. The authors examined the relationship between serum uric acid levels and death from all causes, including cardiovascular disease and stroke. The baseline data were collected in the National Cardiovascular Survey in 1980. The survey was carried out for all household members aged 30 years or older in 300 districts, which were randomly selected throughout Japan. The number who participated in the survey was 10,897. The vital status was ascertained in 1994. Finally, 8172 subjects were available for the analyses. There were 108,284 person-years of follow-up, and 960 deaths from all causes, 249 deaths from cardiovascular disease, and 174 deaths from stroke. After adjustment for age and other cardiovascular disease risk factors, uric acid levels were not associated with mortality from all causes, cardiovascular disease, or stroke. These findings indicate that serum uric acid levels are not related to increased risk for death from all causes, including cardiovascular disease and stroke in a Japanese population.