Urinary albumin excretion as a predictor of the development of hypertension in the general population

The hypothesis that high urinary albumin excretion (UAE; indicating mild renal damage) may precede development of hypertension was tested, and the relation among UAE, GFR, and development of hypertension was investigated. Data of 4635 patients of a prospective cohort study who participated in an extensive screening in 1997 to 1998 and 2001 to 2003 at our outpatient unit and were normotensive at baseline were used. Hypertension was defined according to the Seventh Report of the joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure criteria, UAE was measured in two consecutive 24-h urine samples, and GFR was calculated with the modified Modification of Diet in Renal Disease formula. Mean follow-up was 4.3 yr. Baseline UAE was significantly associated with the risk for developing hypertension (odds ratio 2.29; 95% confidence interval 1.77 to 2.95 per 10-fold increase of UAE). This association was independent of potential confounders. An interaction between UAE and GFR was found (P = 0.030), indicating that with elevated UAE and lowered GFR, but still within the normal range, the risk for developing hypertension was highest. In conclusion, these findings support the hypothesis that mild renal damage may precede the development of hypertension.