Microalbuminuria in subjects with hypertension attending specialist blood pressure clinics

Albuminuria is associated with increased risk of cardiovascular disease and target organ damage in patients with diabetes mellitus. In nondiabetic hypertensive patients, the threshold at which microalbuminuria (MAU) increases risk is unclear and there is evidence that cardiovascular risk may be increased in individuals with MAU levels lower than the usual recommended screening thresholds. We compared two definitions of MAU (on the basis of three early morning urine samples) in a cohort of hypertensive patients attending two specialist clinics in Scotland: conventional (MAU(C)) albumin-to-creatinine ratio (ACR) >2.5–25 mg mmol −1 in males or >3.5–25 mg mmol −1 in females; and low-grade (MAU(L)) ACR 1.2–2.5 in males or 1.7–3.5 mg mmol −1 in females. Of the 1059 subjects screened, 786 (74%) were nondiabetic, with estimated glomerular filtration rate ⩾30 ml min −1 per 1.73 m 2 and without gross proteinuria (low-risk subset). The average age was 58±15 years, body mass index 30±6 kg m −2 and 46% were males. The prevalence of MAU(C) was 11% and 9.5% in the overall and low-risk subset, respectively, whereas MAU(L) prevalence was 11.1% and 10% respectively. The prevalence of cardiovascular disease was higher (24%) with albuminuria (both MAU(C) and MAU(L)) compared with 14% among those without albuminuria. The use of MAU(L) doubled the number of hypertensive subjects with increased cardiovascular risk who can be targeted for more rigorous risk reduction strategies. Consideration should be given to reducing the current threshold for MAU.