Classical xanthinuria is one of the autosomal recessive inherited xanthine dehydrogenase (XDH) deficiencies. Here, we report the rare case of xanthinuria with obstructive urolithiasis in four children. The first patient was a 3-month-old boy who presented with repeated episodes of hematuria and obstructive xanthine stone that resulted in anuria and renal failure. The second case was a 3-year-old girl who was admitted with vomiting and hematuria. She was detected to have a pelvic stone causing urethral obstruction during follow-up. Case 1 and case 2 were third-degree relatives. The third case, a 6-year-old boy referred to our clinic because of hematuria and colicky abdominal pain, was found to have an obstructing ureteral stone. The fourth case was an 18-month-old boy hospitalized for acute pyelonephritis and was diagnosed as having pelvic stones. All the patients had non-opaque stones and screening for metabolic disorders detected markedly decreased urine and plasma uric acid concentrations. High fluid intake and a low-purine diet were recommended for treatment. The examination of the extracted stones with infrared spectrophotometry revealed xanthine and hypoxanthine content. In conclusion, xanthinuria should be considered in patients with non-opaque stone, decreased uric acid concentrations in the urine and plasma. Early diagnosis of xanthinuria may prevent renal damage.
Keywords: Urolithiasis, xanthinuria, children