AN ELEVATED HEMATOGENOUS PHOTOSENSITIZER IN THE PRETERM NEONATE

Purpose. Human blood contains low levels of protoporphyrin IX (PP IX), a photoactive compound that produces reactive oxygen species when exp osed to light. It has been proposed that photoactivation of PP IX and subsequent generation of potentially tissue-damaging reactive oxygen m ay be a mechanism of retinal injury in retinopathy of prematurity (ROP ). The purpose of this study is to determine an association between bl ood PP IX level and infant birth-weight and gestational age. Methods. Erythrocyte PP IX levels were measured from the umbilical cord blood o f 31 neonates, both full term and preterm. Birthweights and gestationa l ages were recorded. Results. PP IX levels in infants weighing < 1000 grams (n = 7) average 200 mug/dl, which is significantly higher than PP IX levels in infants weighing > 1000 grains (125 mug/dl, n = 24; P < 0.02). Conclusion. Elevated PP IX levels may place preterm neonates at increased risk for photosensitizing retinal injury.