[The initial presentation of renal tubular syndrome]

History, clinical presentation and first laboratory results were analyzed in three patients with cystinosis and in three patients with distal renal tubular acidosis. Growth failure, gastrointestinal tract disturbances, polydipsia, and polyuria were the most constant findings on history. Patients with distal renal tubular acidosis had a shorter period of clinical symptoms. All patients presented with dystrophy and dehydration. First laboratory investigation uniformly showed metabolic acidosis, high urinary-pH, and in spite of dehydration a low osmolarity of the first voided urine specimen. There were lower values of serum potassium and of urine osmolarity in cystinosis. In addition, metabolic acidosis was not so pronounced. Our study shows that history, clinical presentation and the results of a few simple laboratory investigations can indicate the presence of a renal tubular disorder even on admission of the patients.