RELATIONSHIPS OF SERUM URIC ACID WITH PLASMA RENIN ACTIVITY AND PLASMA ALDOSTERONE IN PRIMARY HYPERTENSION.

Introduction: In experimental studies conducted in rats, raising serum uric acid (SUA) levels resulted in stimulation of renin expression. Studies in humans exploring the association of SUA with plasma renin activity (PRA) yielded conflicting results. Moreover, little is known about the relationship between plasma aldosterone concentration (PAC) and SUA. Aim: To analyse the relationships between SUA, PRA and PAC in a group of subjects with primary hypertension. Methods: We enrolled 372 patients (mean age 45 ± 12 years; women 33 %), with untreated primary hypertension, with normal renal function and without cardiovascular complications. Results: Spearman’s rank-correlation analyses showed that SUA was significantly associated with PRA and with PAC in the overall study population (rho = 0.127, p = 0.01 and rho = 0.206, p<0.0001, respectively). Age-adjusted SUA levels sere higher in the top tertiles of the distribution of PRA and PAC, when compared to the lower tertiles (p = 0.04 and p<0.0001, respectively). All the associations between SUA, PRA and PAC lost statistical significance in logistic multiple regression analyses aimed at assessing the factors independently associated with an elevation of PRA and of PAC (third tertiles of their distribution). Conclusions: Our results, showing significant relationships of SUA with PRA and PAC only in univariate analyses, seem to suggest that the associations previously reported in some studies between these variables, and particularly that between SUA and PRA, may be mediated by various confounding factors, such as serum creatinine and body mass index.