The renin-angiotensin system (RAS) maintains hemodynamic integrity by modulating both volume and vasoconstriction through a cybernetic feedback control mechanism. In addition, angiotensin II, the active component of the RAS, can be vasculotoxic and, in hypertensive individuals, is associated with increased cardiovascular morbidity and mortality. The objective of this study was to determine the distribution and determinants of plasma renin activity (PRA) in a representative sample of hypertensive persons.

We systematically measured PRA in 4170 untreated participants in a systematic work site-based, hypertension treatment program.

In this multiethnic employed population, patients were classified as follows: low renin, <0.65 ng/mL/h (30% of the sample); medium renin, 0.66 to 4.5 mg/mL/h (60%); or high renin, >4.5 ng/mL/h (10%). Low renin patients were more likely to be African American, female, and slightly older. However, the majority of women and African American individuals were not low renin. The 469 diabetic subjects distributed across renin categories, as did the group as a whole.

This systematic study of PRA in a large community sample of hypertensive patients reveals a wide distribution of activity level, with identifiable differences according to ethnicity, age, and sex but not diabetic status. However, these demographic differences were more quantitative than qualitative and do not provide a useful basis for estimation of the activity of the RAS. Instead, in hypertensive subjects, direct measurement of PRA is necessary, both for prognosis and for guiding hypertensive therapy. Am J Hypertens 2004;17:1–7 © 2004 American Journal of Hypertension, Ltd.