525 TREATMENT OF CYSTINOSIC WITH CYSTEAMINE

Abstract

Attempts at reduction of intracellular cystine in infantile cystinosis, has been reported previously in 3 patients using dithiothreitol (2 patients) or cysteamine (mercaptoethylamine) (1 patient). We evaluated the benefit of a combination of ascorbic acid and cysteamine in a 14-month-old boy with Fanconi's syndrome and cystinosis. The patient's granulocytes contained 5.2 - 13 nmol of cystine/mg of protein (normal < 0.1 nmol/mg protein) and cystine crystals were present in the bone marrow. Creatinine clearance (CCr) was 13 ml/min/1.73 m2 pre-treatment. Ascorbic acid was given as a calcium salt in a dose of 2 mg/kg/day. Cysteamine was given at 99 mg/kg/day. Within 30 days, the buffy coat cystine content had fallen to normal. The dose of cysteamine was then decreased to 30 mg/kg/day. Concurrent with the fall in leukocyte cystine content, the CCr rose to 32.8 and 50 ml/min/1.73 m2 serially and growth improved, though these changes probably reflected other elements of treatment. No side effects were noted. This is the first report of early treatment of cystinosis with cysteamine. Although the long-term benefit of this treatment will not be known for several years, the early satisfactory biochemical response emphasizes the need to evaluate cysteamine in other patients with cystinosis, before the disease is far advanced.