Reduction of proteinuria by indomethacin in patients with nephrotic syndrome.

Immediate and longer-term (five-day) effects of indomethacin on proteinuria and renal function were examined in a group of nephrotic subjects with glomerular filtration rates (GFR) that ranged from near normal to moderately impaired. The modifying role of the patients' sodium/volume (S/V) status on renal prostaglandin inhibition was systematically evaluated by renal clearance and balance studies. After patients were S/V-depleted for five days, indomethacin (75 mg/d) decreased protein excretion by 45%. The decrement in proteinuria was greater than 2 times greater than the fall in creatinine clearance and was unrelated to baseline clearance. In acute clearance studies, 75 mg indomethacin administered orally immediately reduced protein excretion, effective renal plasma flow (CPAH), GFR (C inulin), Na, K, and free water excretion. Indomethacin responsiveness (reduced proteinuria) correlated with the change in PGE2 excretion. The effect of indomethacin on protein excretion and renal hemodynamics was apparent, but blunted, when dietary Na intake was increased to 200 mEq/d. Mean BP increased during indomethacin therapy only when patients were S/V-expanded.