Renin subgroups in essential hypertension: an analysis and critique.

It has been claimed that measurement of renin levels in patients with essential hypertension enables identifiable subgroups of patients to be demarcated and that these subgroups exhibit important differences in prognosis and response to therapy. Accordingly, plasma renin activity (PRA) was measured in 181 patients referred to hospital outpatients for treatment of hypertension. Fifteen of these were excluded from study because of abnormality of renal function, an abnormal pyelogram or incidental disease. PRA of the remainder showed a smooth unimodal distribution with a 'tail' of high values (17%) which lay above the range of values observed in normotensive subjects. Following seven days treatment with bendrofluazide the percentage rise in PRA was much less than that of age-matched controls. A group of 55 patients (33%) fell below the range encountered in normotensive matched subjects treated similarly, although the distribution of PRA was still smooth and unimodal. Patients were divided into 'high', 'normal' and 'low' renin subgroups. Whilst there were significant differences in age between the high, normal and low renin groups, there were no significant differences in basal blood pressure, response to diuretics or beta blockers. It is concluded that renin levels in hypertension are influenced by several factors and that any attempt to subdivide patients into renin subgroups is therefore arbitrary. Measurement of renin does not significantly assist predicting the blood pressure response to either diuretics or beta-blockers combined with diuretics.