HEMATURIA IN CHILDREN: Metabolic Evaluation

Abstract

After excluding nephrological and urologic disorders, recurrent hematuria in children may be related to metabolic disorders. We postulate that the mechanism for hematuria caused by metabolic disorders is increased calcium oxalate crystallization causing tubular epithelial injury. We studid 17 children aged 4 to 14 years (10 M, 7 F) with recurrent hematuria and normal uroradiological studies at the Children's Hospital Ricardo Gutierrez and the Metabolism Section of the Institute of Medical Investigation in Buenos Aires, Argentina. Each child was studied in the Hospital on a stable and neutral diet containing 100 mEq of sodium, 800 mg of phosphorus, and 1200 mg of calcium daily. On the third and fourth day, 24-hour urine samples were collected. On the fifth day fasting venous blood and a 2-hour urine samples were studied for calcium, magnesium, uric acid, phophorus, creatinine, sodium, potassium, oxalic acid, and alkaline phosphatase. The results of the 24-hrs. urine collection (expressed as X + S.D) in mg/kg/24-hrs. were: Ca 4.57 + 0.33, uric acid 13.4 + 2.5, Mg 1.2 + 0.1, and oxalic acid. 68 ± 0.5. The UCa/UCr ratio was 0.24 ± 0.13 for the 24-hrs. urine samples and 0.06 ± 0.03 for the 2-hrs. fasting samples. A metabolic abnormality was detected in 82% (14/17) of the subjects. Hypercalciuria was detected in 47% (8/17) with 35% (6/17) of the renal type and 12% (2/17) of the tubular type. Hypomagnesiuria was detected in 29% (5/17) and both hypercalciuria and hyperuricosuria were seen in one subject (6%). No metabolic abnormality was found in the remaining 18% (3/17). We conclude that children with recurrent hematuria after the exclusion of diseases should be evaluated for metabolic abnormalities as a cause of recurrent hematuria.