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"ALKAPTONURIA" A CASE WITH BLACK URINE

Alkaptonuria is a rare autosomal recessive metabolic disorder that affects one in a million . It is historicaly important as it was the first disease labeled as "Inborn error of metabolism" by Garrod in 1902. Genetic deffects on chromosome 3 cause abnormal production of hemogentisic acid which accumulates in connective tissue and is excreted in urine , thus darkening it . This 22 month old baby from kharanagh came with dark history of urine since three months of age . His mother mentioned that his diapper turned black on standing . In past history there was no pertinent data except consanguinity , without any specific illness in family. Sonographys & IVP, were normal . His urine did not change its color in acidic media . It had a reducing property which was determined by benedict reaction but showed no activity with glucose oxidase reagent . As the other differential diagnoses of black urine were limited phenol poisioing , malignant melanoma porphyria , myoglobinuria. hemoglobinuria with acidic urine and methemoglobin and none of their characterestics were present this diagnosis was made The aim of this presentation is to present the various differential diagnoses of black urine and clinical features of alkaptonuria which can be diagnosed easily by virtue of its clinical features , thus limiting the necessity for further unnecessary investigations .