Plasma hypoxanthine and xanthine levels in the early newborn period in problem-free preterm babies and those with idiopathic respiratory distress syndrome.

The use of hypoxanthine measurements for quantitative monitoring of intrauterine asphyxia is generally accepted. A high level in blood or in CSF is a consequence of tissue hypoxia. Hypoxanthine and xanthine were measured by selective high pressure liquid chromatography in mature newborns, in healthy, symptom-free preterm babies, and in preterm babies affected by idiopathic respiratory distress syndrome. The measurements were carried out from peripheral venous blood within three hours after birth and at the age of 48-72 hours. In mature newborns the mean hypoxanthine level was 11.10 mumol/l in the early determinations, and 8.45 mumol/l in the second set of measurements. In unaffected prematures there were significantly higher levels, and the highest values (44.22 +/- 15.13 mumol/l) were encountered in premature babies subsequently dying of severe hypoxia. Xanthine showed a similar course. In addition to establishing normal values for prematures we desired to clarify the changes in the levels of purine metabolites during idiopathic respiratory distress and their prognostic value. Hypoxanthine and xanthine levels were found to be informative in postnatal hypoxia, especially together with other parameters.