1 From the Department of Pediatrics, Institute of Forensic Medicine and Institute for Surgical Research, the National Hospital, Oslo
To test whether or not premature babies at risk for retinopathy of prematurity have elevated hypoxanthine levels in the eye, the vitreous humor of 13 premature babies who died of severe respiratory distress syndrome and lung failure, was analyzed for hypoxanthine. Their hypoxanthine level was 459 ± 171 µmol/L (mean ± SD) compared with 54 ± 71 µmol/L in seven newborn babies who died suddenly (P < .001). In 53 adults who died suddenly, the hypoxanthine concentration was 136 ± 119 µmol/L (P < .001 when compared with babies with respiratory distress syndrome). Babies with respiratory distress syndrome underwent a significantly longer period with arterial Po2 levels less than 40 mm Hg (5.3 kPa) and they required supplementation with 100% oxygen significantly longer than control babies. The hypoxanthine concentration was correlated with the time during which the arterial Po2 was lower than 40 mm Hg (5.3 kPa) before death, and a significant positive correlation was found (R = .59, P < .012). The study shows that high levels of hypoxanthine are found in vitreous humor of premature babies with respiratory distress syndrome. Because hypoxanthine is a potential oxygen radical generator and premature babies might have lower levels of antioxidants than full-term babies, it is suggested that the hypoxanthine accumulation in the eyes of premature babies with respiratory distress syndrome could play a pathogenetic role in the development of retinopathy of prematurity.
Key Words: hypoxanthine oxygen radical retinopathy of prematurity vitreous humor respiratory distress syndrome
Submitted on January 27, 1987
Accepted on June 16, 1987