The various renal manifestations of the nephropathic form of cystinosis.

Three phenotypic forms of cystinosis (nephropathic, juvenile-onset and benign adult forms) are well recognized. That not all infants and children have the classical nephropathic form with Fanconi's syndrome is illustrated by 2 of the 3 patients in this report. Case 1 had the typical nephropathic form with generalized proximal tubular dysfunction. In contrast, case 2 had transient features of Bartter's syndrome which preceded the manifestations of Fanconi's syndrome. Case 3 was more complex because he first presented with a syndrome of nephrogenic diabetes insipidus. He then developed features of Fanconi's syndrome as well as metabolic acidosis, hyponatremia and hyperkalemia. The failure of deoxycorticosteroid administration to elevate the serum concentration suggested, in retrospect, that he may also have had a form of acquired pseudohypoaldosteronism.