Plasma renin activity and plasma prorenin are not suppressed in hypertensives surviving to old age

An age related decline in plasma renin activity (PRA) has been described in normotensive and hypertensive subjects. Moreover, hypertensive patients are reported to have lower plasma prorenin levels. We therefore investigated whether that pattern of renin and prorenin suppression was apparent in white hypertensives and normotensives surviving to an older age. The study population consisted of 65 untreated hypertensives (office blood pressure greater than or equal to 160/95 mm Hg; mean age 79 +/- 6 SD; range 69 to 94 years) and 26 normotensives (mean age 77 +/- 8; range 66 to 99 years). The PRA in this population of older hypertensives (1.7 +/- 1.6 ng/ml/h) was not significantly different from normotensives of similar age (1.5 +/- 0.8 ng/ml/h). PRA was not correlated to age in either normotensives and hypertensives, but was inversely correlated to office blood pressure in the hypertensives (r = -0.25; P = .05). Plasma prorenin was also not significantly lower in older hypertensives (14.6 +/- 8.6 ng/ml/h) than in the normotensive controls (15.1 +/- 7.0 ng/ml/h). In normal subjects, but not in hypertensive patients, there was a positive relationship between plasma prorenin and age (r = 0.82; P <.001). However, elderly normotensive men had lower plasma prorenin levels (11.6 +/- 4.1 ng/ml/h) than normotensive women (18.6 +/- 7.4 ng/ml/h; P <.05). ''Total renin'' (PRA + plasma prorenin) was also lower in elderly normotensive men compared to women (13.2 +/- 3.9 ng/ml/h v 20.0 +/- 7.5 ng/ml/h; P <.05). In conclusion, neither PRA nor plasma prorenin are suppressed in normotensive or hypertensive subjects who survive to an old age. However, since an inverse relationship between PRA and age has been reported, it remains to be determined whether the renin/prorenin parameters were suppressed at any time or if normal renin and normal prorenin patients preferentially survive to an old age. The wide spectrum of plasma renin levels in the elderly indicates that treatment of these patients too can profitably be guided by pretreatment plasma renin levels.