Light-Chain Nephropathy

Abstract

We observed idiopathic light-chain proteinuria in a patient with multiple abnormalities of proximal-tubule transport mechanisms (Fanconi syndrome), nephrogenic diabetes insipidus, and distal renal tubular acidosis. Seventeen of the 19 urinary amino acid levels measured were elevated. Uric acid and phosphate clearances were greater than 60 per cent and 50 per cent, respectively, of the simultaneous inulin clearance. When water deprivation was coupled with vasopressin administration, the maximum urinary concentration observed was 384 mOsm per kilogram of water. During ammonium-chloride loading, the level of hydrogen-ion concentration in the urine remained less than 100 times that in the blood. Kappa light-chain excretion was 149 mg per 24 hours.