Comparative therapeutic benefit of indomethacin, hydrochlorothiazide, and acetyl-salicylic acid in a patient with nephrogenic diabetes insipidus.

To define the importance of renal prostaglandins in nephrogenic diabetes insipidus (NDI), diuresis and the urinary excretion of PGE2 and PGF2 alpha were studied in a patient with NDI before and during inhibition of endogenous prostaglandin synthesis with either indomethacin (IND) or acetyl-salicylic acid (ASA). The excretion rates of PGE2 and PGF2 alpha were in the low normal range for the patient's age group, remained unchanged during 6 h of fluid deprivation and were suppressed by IND (150 mg/day), ASA (3 g/day), and by the combination of IND and hydrochlorothiazide (HCT, 50 mg/day). However, whereas IND, HCT, and the combination of IND and HCT reduced diuresis ASA did not. Free water clearance as determined during fluid deprivation remained positive during each phase of therapy. These data fail to demonstrate a direct effect of endogenous ADH on renal prostaglandin synthesis in NDI. The ineffectiveness of ASA to reduce diuresis indicates that indomethacin affects diuresis in NDI by a mechanism other than inhibition of cyclooxygenase.