Reduced renin activity in essential hypertension: a reappraisal

The apparent suppression of plasma renin activity in essential hypertensive patients compared to normotensive controls prompted an examination of factors which might be responsible for this difference in people taken from a blood pressure screening survey. Plasma renin activity was lower in 89 previously untreated "hypertensive" subjects than in an equal number of age- and sex-matched "controls" from the same community. The rise in plasma renin activity on standing or after frusemide was proportional to the resting level, and it was generally less in hypertensives, but small or absent responses were also seen in those with normal blood pressure. There was no evidence for a "low renin sub-group" among the hypertensives. Plasma renin activity fell with both increasing age and increasing arterial pressure. A low renin activity is more likely to be a consequence of hypertension than to be associated with its cause.