Cystinuria: the South Indian experience.

[cystinuria]

Cystinuria is reportedly a rare condition affecting the stone patients in India . This paper presents the occurrence of cystine-related abnormality in the population of stone patients reporting to the hospitals in South India . Two thousand and eight hundred urine samples from 1 ,300 patients attending the urinary stone clinic during the period 2004 -2008 were assessed for cystinuria by performing the nitroprusside test on the early morning urine and random samples on the day of attendance . Urinary deposits were also studied in all the patients . Stones retrieved from 800 stone patients were analysed qualitatively and by Fourier Transform infra red (FTIR ) spectroscopy . Cystinuria was identified in only three patients . None of these patients showed cystine crystals . Three other patients out of the 1 ,300 showed presence of cystine crystals in the urine deposit . FTIR spectroscopy of the stones retrieved from the patients showed presence of cystine in 19 out of the 800 stones analysed (2 .375 %). None of the patients with cystine in the stones had either cystine crystals in the urine or positive nitroprusside test for cystine . All the patients who had positive cystine , cystine crystals or cystine in stone analysis had other biochemical abnormalities . They were medically managed with appropriate biochemical corrective chemotherapy and had control of stone disease process . All the patients were advised purine restriction in the diet . It is concluded from the study that cystinuria is a rare entity in South India . It , however , exists in a small percentage of stone patients . Specific treatment with D-penicillamine was not administered to the patients in view of the high cost , nonavailability and possible toxicity . The patients considered above did not have intractable stone disease which was not amenable to usual modalities of directed medical therapy .