Cistinosis nefropática infantil

Abstract

Nephropathy caused by cystinosis is a rare recessive disorder produced by a defect in the lysosomal transport of cysteine. This results in intracellular crystal deposits in the kidneys, cornea and other tissues. It constitutes the commonest congenital cause of Fanconi's syndrome and progresses during the first decade of life to chronic renal failure. The diagnosis is confirmed by the detection of cystine in circulating leucocytes and lymphoblasts. The treatment consists in replacing the losses caused by the tubular defect and the oral administration of cystamine which depletes cystine and favours its transport across the lysosomal membrane. The objective of this report is to present the first case of cystinosis diagnosed and treated in Chile. The patient was hospitalized at the age of 15 months with advanced disnutrition, clinical rickets, severe dehydration, hypokalaemia, hypophosphataemia, metabolic acidosis consistent with Fanconi's syndrome. An elevated concentration of cystine was found in the polymorphic leucocytes confirming the diagnosis. After 2 years of treatment with oral cystamine the patient demonstrates an excellent evolution with regards to stature and conservation of renal function, although the tubular defect persists.