[Xanthinuria type I as the cause of nephrolithiasis in 17-years old girl].

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Classic xanthinuria is a rare metabolic defect concerning the final reactions of purine catabolism . There are two types of the disorder : type I results from xanthine dehydrogenase (XDH ) deficiency , while type II is characterized by lack of both XDH and aldehyde oxidase activity . Both types are clinically similar and are characterized by elevated xanthine concentration in body fluids that can lead to xanthine crystallisation . The most common manifestation of the disease is urolithiasis , but in most cases xanthinuria remains asymptomatic and the diagnosis is accidental . In the paper we report the first case study of xanthinuria in Poland in a child presenting with urolithiasis . 17 -years old female patient was diagnosed because of recurrent urinary lithiasis and hypouricemia was detected during routine tests . Plasma and urine concentrations of oxypurines were measured by high -performance liquid chromatography (HPLC ) and showed typical features of xanthinuria : hypouricemia , hypouricosuria , xanthinuria and elevated plasma xanthine . The allopurinol loading test demonstrated type I xanthinuria . The presented case report supports that first symptoms of xanthinuria can appear at any age and this disorder should be considered during diagnosing urolithiasis .