THE TREATMENT OF CYSTINOSIS WITH CYSTEAMINE AND PHOSPHOCYSTEAMINE IN THE UNITED-KINGDOM AND EIRE

Fifty-nine patients with cystinosis were treated with cysteamine or ph osphocysteamine in the United Kingdom up to May 1990. Treatment was st arted at a median age of 3.2 years (range 0.6-24.8 years) and continue d for a median duration of 3.0 years (range 0.01-1.2 years). At the en d of the study, 46 (78%) patients remained on treatment. One patient d eveloped end-stage renal failure and 6 died. Efficacy was assessed in the 44 pre-transplant patients, The United Kingdom pre-transplant pati ents had significantly lower plasma creatinine concentrations at 6 and 8 years than a historical group of patients who did not receive cyste amine (P<0.0001 and P<0.0003, respectively). There was no significant difference between pretreatment and final post-treatment height standa rd deviation scores, suggesting maintenance of growth rate. The leucoc yte cystine concentration was less than the accepted upper limit of th e treatment range (1 nmol 1/2 cystine/mg protein) in only 21% of deter minations, There was no significant difference between the mean pre-tr eatment and final values of leucocyte cystine concentration. The mean final doses of cysteamine (33 mg/kg per day) and phosphocysteamine (37 mg/kg per day base equivalent) were less than the mean dose (51 mg/kg per day) used in a United States multicentre trial. We conclude that cysteamine treatment was beneficial, but further improvements might be achieved by an improvement in monitoring of therapy.