Plasma renin in hypertensive patients: significance in relation to clinical and other biochemical features.
Presenting features of 221 hypertensive patients were examined in relation to plasma renin. One hundred and seventy-six patients had essential hypertension, of these 47 had high plasma renin activity (PRA), 80 had normal PRA and 49 low PRA. When the groups with high and low PRA were compared with age and sex matched patients with normal PRA there was no difference with respect to clinical, radiological, electrocardiographic and biochemical characteristics. Twenty-five patients had radiological evidence of unilateral renal or renovascular disease and twenty patients had accelerated hypertension with advanced fundal changes: both these groups had more severe hypertension, a higher plasma renin and evidence of greater cardiovascular morbidity than patients with essential hypertension. Morbidity was equally high in patients with accelerated hypertension whether PRA was high or normal. There is therefore no evidence to support the view that renin is an important factor in assessing risk in hypertension. If, on the other hand, specially referred patients with renovascular and accelerated hypertension are pooled with other hypertensive patients, a spurious association between renin and cardiovascular morbidity will be created.