Laragh, Heinemann, and Demartini first reported that the administration of chlorothiazide during water diuresis results in an increased rate of solute excretion without significant changes in the rate of urine flow (1,2 repeatedly confirmed (6-13), and the thiazide derivatives have now attained a place of therapeutic usefulness in patients with vasopressinresistant diabetes insipidus (13).Inhibition of solute reabsorption in the distal nephron alone does not account for the antidiuretic effect of the thiazide derivatives. As indicated above, such inhibition of solute reabsorption would merely increase urinary osmolality without affecting urinary volume. Therefore, the mechanism whereby volume is reduced must reside in some other direct or indirect action of these agents. The results of the present studies are consistent with the view that the antidiuretic effect of hydrochlorothiazide is a consequence of the losses of sodium induced by the agent and is not due to any unique property of the thiazide derivatives. The antidiuresis is enhanced by a low sodium intake. is diminished by a high sodium intake, and may also be produced by mercurial diuretics, despite apparent differences in the site and mode of action of the latter agents.
METHODSMultiple studies were performed on four hospitalized male subj ects with vasopressin-resistant diabetes insipidus, ranging in age from seven to, seventeen years. Two were brothers, a third had an affected brother, and all had a history of polyuria and polydipsia dating from infancy. Maximal urine osmolalities after a 17-to 20-hour thirst were less than 100 mOsm per kg in three subjects, and not greater than 130 mOsm per kg in one subject (S. Z.). None of the four subjects demonstrated any increase in urinary concentration when dehydration was followed by the administration of vasopressin. All were free of other renal functional abnormalities. The intakes of sodium were controlled by the addition of weighed amounts of sodium chloride to a standard diet containing 9 mEq of sodium. In all instances in which the effects of hydrochlorothiazide were studied, the drug was administered orally, 25 mg every 8 hours. A mini-1988