Ratio of the concentration of hypoxanthine to creatinine in urine from newborn infants: a possible indicator for the metabolic damage due to hypoxia.

The ratio of the urinary concentrations of the ATP metabolite, hypoxanthine, to that of creatinine was determined in normal newborn infants. An increase in this ratio reflects high hypoxanthine excretion and thus ATP breakdown. The ratio can be determined on random urine samples, thus simplifying sampling. Urinary changes are persistent; abnormalities are detectable on the second day of life after intrapartum hypoxia. Preliminary results suggest that this ratio on a sample during the second day of life could 'diagnose' intrapartum hypoxia and might therefore quantitatively assess those obstetric 'risk factors' believed to operate through hypoxia.