The relationship between low plasma renin activity, low serum ionic calcium, and elevated systolic arterial tension...

Plasma renin activity, plasma and urinary aldosterone, and serum and urinary calcium and magnesium were studied in forty elderly normotensive subjects and 37 normotensive young adult controls. Arterial tension was also recorded for each subject. The most important findings were significantly lower levels (P less than 0.001) of plasma renin activity, urinary aldosterone, and serum ionic calcium in the elderly group. A significant positive correlation was shown between calcium and plasma renin activity (P less than 0.001); an inverse correlation was found between systolic arterial tension and calcium (P less than 0.001). These findings indicate age-related physiological changes between the renin-aldosterone system, calcium, and systolic arterial tension. These changes are similar to those found previously in young adult hypertensives with low plasma renin activity levels, suggesting that the arterial tension of the elderly is labile, and that changes in the renin-angiotensin-aldosterone system (RAA) and calcium levels directly influence the increase of systolic arterial tension, which is frequently found in the elderly.