Renal dysfunction as a possible cause of essential hypertension in predisposed subjects.

In 65 young normotensive subjects with two hypertensive parents (HP), and in 55 matched subjects with two normotensive parents (NP), the following factors were measured: renal plasma flow (RPF), glomerular filtration rate (GFR) both as Inutest and creatinine clearances; 24-hr urinary output; plasma renin activity (PRA); Na and K in plasma and in 24-hr urine and 24-hr urinary excretion of aldosterone. In 30 HP and in 34 NP, the cardiac output and plasma concentrations of noradrenaline, adrenaline, and dopamine were also measured in the supine position and after 10 min of standing. The HP have greater RPF (P less than 0.01), faster GFR (P less than 0.02), greater 24-hr urinary output (P less than 0.05), and lower PRA (P less than 0.01) than the NP. All the other factors were similar in the two groups of patients. It is proposed that the differences in renal function in the HP and the NP may be due to an abnormality in tubular handling of ions and water in the HP, which may be responsible for the increase in blood pressure in a proportion of patients with essential hypertension.