Uric acid as a marker for renal dysfunction in hypertensive women on diuretic and nondiuretic therapy

Hyperuricemia is a common finding in hypertensive patients, especially among those who are on diuretic therapy. However, its clinical relevance regarding cardiovascular and chronic kidney disease (CKD) has not clearly been established. The authors assessed whether, in a population of 385 hypertensive women categorized according to diuretic therapy, the stratification in quartiles by uric acid levels would identify a gradient of changes in renal function and in risk factors for cardiovascular disease. The following were evaluated: serum uric acid, glycemia, total and fractional cholesterol, triglycerides, apolipoprotein (Apo) B, Apo A-I, and C-reactive protein. Renal function was assessed by serum creatinine, albuminuria, and estimated glomerular filtration rate (eGFR) by the Modification of Diet in Renal Disease equation, whereas cardiovascular risk was estimated through the Framingham score. A total of 246 women were on diuretic therapy; 139 were taking other antihypertensive medications. There was a reduction in eGFR parallel to the increase in uric acid levels, regardless of diuretic use and without a concomitant increase in albuminuria. In both groups, higher uric acid levels translated into an increase in metabolic syndrome components, in markers of insulin resistance, triglyceride / high-density lipoprotein levels, and Apo B/Apo A-I ratios, as well as in Framingham scores. Hyperuricemia was associated with an increase in inflammatory markers only in patients on diuretic therapy. In a binary logistic regression, hyperuricemia (uric acid >6.0 mg/ dL) was independently associated with CKD (eGFR <60 mL/ min / 1.73 m(2)) (odds ratio, 2.63; 95% confidence interval, 1.61-4.3; P<.001). In hypertensive women, the presence of hyperuricemia indicated a substantial degree of kidney dysfunction as well as a greater cardiovascular risk profile.