A 6-month-old black girl had chloride-losing diarrhea. The patient's condition was evaluated prior to and following treatment with sodium chloride, potassium bicarbonate, a combination of sodium chloride and potassium chloride, and potassium chloride alone. Serum chloride levels increased progressively with increasing intake of potassium chloride with or without sodium chloride, but not with sodium chloride alone. Stool concentrations of chloride remained elevated, and urinary chloride excretion remained low despite high chloride intake on all regimens.
Both potassium and chloride supplementation in quantities approaching maximum tolerance (250 millimols/sq m/day), appeared to be necessary for fluid and electrolyte homeostasis in this patient.
A renal biopsy specimen disclosed hyperplasia of the juxtaglomerular apparatus, suggesting hyperreninism. Vascular lesions were also noted.