How many Iranian Cystinosis patients Uses Right Dosage of Cystagon

Background: cystinosis is a metabolic autosomal recessive disorder caused by mutation in cystinosin (CTNS) gene, locus 17p131–3 and lead to accumulation of cystine crystals in lysosomes. We conducted guided discussion regarding specific topic , to explore how many of patients use recommended dose of cystagon and how many of them are under treated .Methods: we gathered information on 185 cystionis patients from the whole country. They were diagnosed by the specialists through eye examination, WBC cysteine level and bone marrow analysis. Among these 185 patients, 40 live in Tehran, 35 in Ahvaz , 18 in Isfahan , 13 in Urmia ,6 in Mashhad , 29 in Shiraz ,10 in Tabriz , 2 in Rasht and 2 in Gorgan.The recommended dose in these patients was evaluated base on patient’s height and body weight. These doses were then compared to the actual daily dose of each patient.Results & Discussion: We found that 42% of patients are treated with lower dose than recommended and among them 26% are taking as low as half of the therapeutic dose. This can be explained by patient’s compliance, financial issues and physician’s experience. When treatment is optimized (recommended dose for <50 kg is 1.3g/m2/day and for > 50 kg is 2 g/day), we encounter less side effects and higher life expectancy. Cystagon’s dosing should be based on the body surface area and calculated in g/m2/day. We strongly suggest our physicians to prescribe Cystagon with the correct dosage for the successful treatment regardless of patients compliance or cost.