RELATIONSHIP BETWEEN SERUM URIC ACID AND AORTIC STIFFNESS IN UNTREATED HYPERTENSIVE SUBJECTS

Recent studies have reported an association between serum uric acid (SUA) and reduced arterial elasticity. However, in these studies arterial elastic properties have been assessed chiefly by measuring brachial-ankle pulse wave velocity (PWV) or peripheral PWV and only sometimes by using aortic PWV. Moreover, the relationships between SUA and arterial stiffness have never been statistically adjusted for albuminuria. Furthermore, the studies exploring the influence of uric acid on aortic distensibility in subjects with arterial hypertension yielded conflicting results. The aim of our study was to evaluate the relationships between SUA and aortic stiffness in a group of essential hypertensive patients, attending our Hypertension Centre. We enrolled 222 untreated hypertensive patients (mean age: 44 ± 10 years; 60 % males), without cardiovascular complications and without severe renal insufficiency. In all subjects routine blood chemistry, including SUA determination (by uricase/peroxidase method) and albumin excretion rate (AER) assay were obtained. Moreover, measurement of carotid-femoral pulse wave velocity (c-f PWV), by an automatic computerised method (Complior) and 24-h ambulatory blood pressure (BP) monitoring were performed. Patients with c-f PWV > 12 m/sec (n = 44) showed SUA levels significantly higher than those with lower values of PWV (5.9 ± 1.2 vs 5.3 ± 1.1 m/sec; p = 0.002). This difference held after correction by ANCOVA for age, gender, mean arterial pressure (MAP), body mass index, and serum creatinine (p = 0.02), but not after further adjustment for AER. Univariate analysis of correlation disclosed a significant association of SUA with c-f PWV (r = 0.23; p = 0.001). This correlation lost statistical significance when AER was added in a multiple regression model including, as covariates, age, gender, MAP, serum creatinine, metabolic syndrome and SUA. The results of our study show that, in essential hypertensive subjects, a positive relationship between SUA and aortic stiffness exists This association may be mediated by endothelial dysfunction, as suggested by the loss of its statistical significance, after adjustment for albumin excretion rate.