The effects of cysteamine on the upper gastrointestinal tract of children with cystinosis.

The purpose of this study was to evaluate the effects of cysteamine on gastric acid output and serum gastrin levels in children with nephropathic cystinosis. We studied four children with nephropathic cystinosis receiving a dose of free base cysteamine of 14.35 mg/kg four times a day (range 12.30-18.80 mg/kg). Gastric acid was measured for the hour before and after administration of the medication. Serum gastrin levels were obtained at 0, 30, 60, and 90 min following the medication. Gastrointestinal anatomy was evaluated by endoscopy and biopsy. Following administration of the medication, all subjects showed an increase in gastric acid output. Mean acid output increased from 0.79 to 2.22 mEq/h. Mean gastric acid output adjusted for body weight increased from 0.03 to 0.09 mEq/kg per hour. Following administration of the medication, all subjects showed an increase in serum gastrin. The mean increase above the base value was 38.3 pg/dl. Two of the four subjects demonstrated visual and histological evidence of inflammation. Cysteamine has a marked effect on gastric acid production and serum gastrin, even at the dose used in children with nephropathic cystinosis. The clinical effect of this acid production is unknown but may be significant.