Fanconi syndrome with renal sodium wasting and metabolic alkalosis

A boy with idiopathic Fanconi's syndrome is described who exhibited, in addition to the usual features, an unusually large degree of urinary sodium chloride wastage accompanied by a metabolic alkalosis. No evidence of distal tubular abnormality was found and all urinary findings were explicable on the basis of proximal tubular malfunction. Investigations revealed that a combination of sodium, chloride and potassium depletion produced an alkalosis despite the presence of a low bicarbonate threshold commonly found in this syndrome. Detailed studies suggested that although potassium depletion may play a smaller role than sodium chloride wastage, its effects are real and in some degree mediated by an effect upon proximal tubular bicarbonate reabsorption.