A patient with cystinosis presenting transient features of Bartter syndrome.

A 16-month-old boy was admitted to the clinic because of vomiting and growth failure. His weight and height measurements were under the fifth percentile. He had fair hair and skin, enlarged wrists and rachitic rosaries. The presence of metabolic alkalosis, hypokalemia, hypochloremia, and high renin and aldosterone levels were suggestive of Bartter syndrome. However, in view of the growth failure, fair hair and skin, proteinuria, polyuria and active rickets, cystinosis was considered. Bone marrow smear examination was normal, despite the existence of suspicious crystals in the cornea. Cystine crystals were seen in the conjunctiva biopsy and increased leukocyte cystine level was measured; therefore, definitive cystinosis diagnosis was made. Renal Fanconi syndrome with metabolic acidosis is prominent in cystinosis; however, in rare instances, if sodium-dependent trans-tubular transport defect is present, patients could have Bartter syndrome findings such as hypochloremic metabolic alkalosis. Our case is a good example demonstrating that metabolic alkalosis should not exclude cystinosis and the other signs and symptoms of the patient should be thoroughly evaluated.