Urinary Albumin as a Marker of Future Blood Pressure and Hypertension in the General Population

We investigated whether urinary albumin could predict the development of hypertension and future increases in blood pressure in the normotensive general population. Normotensive subjects who visited our hospital for a physical checkup (n = 6205, men 61.8%, 53.4 ± 11.4 years old) were enrolled in this study. Urine samples were collected for the measurement of albumin concentration, expressed as the ratio of urinary albumin to creatinine concentrations (UACR [mg/g Cr]). After the baseline examination, subjects were followed up for a median of 1089 days with the endpoint being the development of hypertension. Urinary albumin was in the normal range (UACR <30 mg/g Cr) in most subjects (97.5%). During the follow-up, hypertension developed in 1184 subjects (19.1%, 69.5 per 1000 person-years), with more men than women affected. The incidence of hypertension was increased across the quartiles of UACR by Kaplan–Meier analysis (log-rank, P < 0.0001) and the hazard ratio (lowest quartile [median UACR 1.14 mg/g Cr] as reference) was 1.53 (95% confidence intervals 1.30–1.80) in the highest quartile (median UACR 8.87 mg/g Cr). Multivariate Cox hazard analysis in which UACR was taken as a continuous variable identified UACR as a significant predictor of hypertension (hazard ratio 1.37, 95% CI 1.20–1.56). UACR was also an independent predictor of future increases in systolic blood pressure (P < 0.01). Urinary albumin is an independent predictor of hypertension and increases in blood pressure in the general population even in the normal range below the threshold defined for microalbuminuria.