The serum
uric acid level has been said to be an independent predictor of
cardiovascular disease death, mainly for women, and to be linked with the
metabolic Syndrome X of
insulin resistance,
obesity,
hypertension, and
dyslipidemia. Recently, it has been suggested that the elevation of serum
leptin, the
ob gene product, may have a role in
metabolic Syndrome X. Therefore, we studied the relationship of
uric acid to
leptin in 822 Japanese women in a cross-sectional manner. To estimate the effect of
uric acid on the variables of
metabolic Syndrome X, we calculated mean values of various components of the syndrome according to tertiles of
uric acid (UA < 4.0 mg/dl, 4.0 < or = UA < 5.5, 5.5 < or = UA). Age, systolic and diastolic blood pressure (BP), body mass index (BMI), percent body fat mass (BFM), serum total
cholesterol,
triglyceride, atherogenic index,
leptin, fasting immunoreactive
insulin and homeostasis model assessment-ratio (HOMA-R: calculated
insulin resistance) were significantly different across the
uric acid tertiles with higher levels in the highest tertile in comparison to the first (ANOVA, p < 0.001, 0.001, 0.002, 0.001, 0.001, 0.025, 0.001, 0.001, 0.001, 0.001, 0.001, respectively), while
high density lipoprotein cholesterol showed lower levels (p < 0.001). Serum
leptin concentrations were also elevated in hyperuricemic women after adjusting for BMI or BFM (both p < 0.001), and were weakly correlated with serum
uric acid concentrations (r = 0.22, p < 0.0001). BMI, HOMA-R, serum
triglyceride, diastolic BP and age-adjusted serum
leptin concentrations were calculated for each tertile of serum
uric acid. Compared with the lowest tertile of
uric acid level, BMI, HOMA-R, serum
triglyceride, diastolic BP and age-adjusted
leptin concentrations were higher in the highest tertile. In the stepwise regression analysis, serum
leptin was the significant independent variable for
uric acid values. These results indicate an independent relationship between
leptin and
uric acid, further supporting the involvement of
leptin in
metabolic Syndrome X.