Oxypurine excretion in normal newborn infants.

Hypoxanthine, xanthine, uric acid, 6-hydroxypurine, 2,6-hydroxypurine and 2,6,8-hydroxypurine, respectively, are the catabolic products of purine-containing compounds in the human body. Each of the compounds was determined, by enzymatic spectrophotometry, in the 24-hour urine samples of 23 newborn infants. The hypoxanthine excretions on the 1st, 2nd and 3rd days were 1.1 (0.7-1.6), 0.9 (0.1-1.4) and 0.7 (0.1-1.5) mumol/24 h/kg body weight. The xanthine excretion in the 1st, 2nd and 3rd days was: 0.5 (0.3-1.2), 0.6 (0.3-2.0) and 1.2 (0.4-1.9) mumol/24 h/kg body weight. The uric acid excretion in the 1st, 2nd and 3rd days was: 61 (33-150), 61 (20-142) and 76 (40-127) mumol/24 h/kg. All the values are given as median and 10% percentiles. The hypoxanthine excretion decreased significantly (p less than 0.05) and the xanthine increased correspondingly throughout the 3 days (p less than 0.05). The excretion of hypoxanthine plus xanthine showed no significant change throughout the 3 days, and comprised approximately 2.5% of the total oxypurine excretion.