Relationship between severity of essential hypertension and hyperuricemia

BACKGROUND: Hyperuricemia has been associated with an increased risk of car diovascular disease in hypertensive patients. However, the relation between serum orate and severity of hypertension has not been conclusively defined as yet. We aimed at finding out whether there exists an independent relati onship between changes in the prevalence of hyperuricemia and severity of h ypertension. PATIENTS AND METHOD: We studied 3 cohorts of patients aged 35 to 60 years w ith essential hypertension la diagnosed at a university hospital in Madrid, Spain. The first cohort (before 1981) included 325 patients, the second (f rom 1981 to 1989) comprised 271 patients and the third cohort (from 1990 to 1999) included 545 patients. Disease severity ranged from 1 to 6 according to blood pressure levels at diagnosis (WHO/ISH grades 1, 2 or 3 were assig ned 1, 2 or 3 points, respectively) and target organ damage (left ventricul ar hypertrophy, hypertensive retinal vascular changes, and proteinuria abov e 3 mg/day; one point each). RESULTS: Mean serum urate concentrations in the 3 cohorts were 6.6, 5.8 and 5.5 mg/dL, respectively. (p < 0.05 for all comparisons). 39% of patients i n the first cohort had a serum orate concentration > 7.0 mg/dL whereas only 18.1% patients in the third group showed hyperuricemia (difference: 20.9%; 95% CI, 10.1 to 32.3; p < 0.05). Severity of hypertension was higher in th e first cohort (mean <plus/minus> SD 2.50 +/- 1.31 points) than in the thir d group (1.96 +/- 1.06 points; p < 0.05), with the second cohort showing an intermediate severity (2.23 <plus/minus> 1.01 points). Serum orate levels were directly related to the severity of hypertension in the 3 groups (r = 0.08, p < 0.05). In a multivariate analysis, after adjustment for confoundi ng variables, serum gyrate had no significant association with severity of hypertension. However, target organ damage, systolic blood pressure and ser um creatinine were all independent predictors of severity. CONCLUSIONS: Favourable changes in the severity of hypertension for a time period significantly correlate with decreases in hyperuricemia prevalence i n the same period. On the other hand, hyperuricemia appears to be an indire ct marker of hypertensive renal damage.