Renin-angiotensin-aldosterone system during chronic thiazide therapy of benign hypertension.

SUMMARY Activity of the renin-angiotensin-aldosterone system was investigated in 53 patients with benign essential hypertension treated with thiazides. Following acute (less than 3 weeks) exposure to thiazide, renin activity was increased in peripheral plasma and sensitivity to infused angiotensin was decreased but only when dietary salt was simultaneously restricted. During chronic (more than 2 months) exposure to hydrochloro-thiazide, 32 patients with unrestricted salt intake had normal renin activity in peripheral plasma (39 of 43 determinations), normal sensitivity to infused angiotensin (18 of 22 tests), and normal aldosterone excretion (nine of nine assays). Renin activity correlated well with angiotensin sensitivity (r =0.661; P < 0.001). Therefore, chronic ingestion of thiazide apparently induces no change in the renin-angiotensin-aldosterone system and hence presumably neither secondary aldosteronism nor negative sodium balance.