[A case of Bartter's syndrome with chronic renal failure due to chronic interstitial nephritis].

We report a case of 45-year-old women with Bartter's syndrome and concomitant renal dysfunction. In 1986, the patient demonstrated muscle weakness and serum potassium levels as low as 1.1 mEq/l. She was suspected of having Bartter's syndrome because of hypokalemia, metabolic alkalosis, hyperreninemia, hyperaldosteronism and normotension. Pretibial edema developed in 1989 for which she received 40 to 100 mg/week of furosemide intermittently for the next 5 years. Her serum potassium level ranged from 1.5 to 3.9 mEq/l. In 1991, her serum creatinine level rose to 2.1 mg/dl, then continued to increase gradually. She was admitted to our hospital in 1994 for evaluation of the renal dysfunction. Decreased creatinine clearance (44 ml/min) and a defect in urinary concentrating capacity (Fishberg's test, 370 mOsm/kg.H2O) were detected. Renal biopsy revealed juxtaglomerular cell hyperplasia. These findings resulted in the diagnosis of Bartter's syndrome. The renal biopsy also showed diffuse interstitial fibrosis and marked tubular atrophy. We postulate in this case that long-term hypokalemia due to Bartter's syndrome and the administration of furosemide led to chronic interstitial nephritis and renal dysfunction.