Salt intake and diuretic treatment of hypertension

24 h urinary sodium excretion was used to monitor salt intake in 36 patients with essential hypertension to determine whether limitation of the antihypertensive action of thiazide diuretics could be explained by increased salt appetitie stimulated by salt depletion. Sodium excretion in these patients was similar before treatment to that observed in normotensive controls, and no change was observed during 2 years' treatment with bendrofluazide. However, plasma-renin rose progressively over the 2 years even in 5 of 8 patients whose renin was not stimulated initially by diuretics. Thus, there is no evidence that a voluntary increase in salt intake limits the efficacy of diuretic treatment; on the other hand, progressive stimulation of the renin-angiotensin system may be an important limiting factor to the antihypertensive action of diuretics. If so, the antihypertensive effect of dietary salt restriction may be similarly limited.