An elevated hematogenous photosensitizer in the preterm neonate.
OBJECTIVE
Human blood contains low levels of protoporphyrin IX (PP IX), a photoactive compound that produces reactive oxygen species when exposed to light. It has been proposed that photoactivation of PP IX and subsequent generation of potentially tissue-damaging reactive oxygen may be a mechanism of retinal injury in retinopathy of prematurity (ROP). The purpose of this study is to determine an association between blood PP IX level and infant birth-weight and gestational age.


METHODS
Erythrocyte PP IX levels were measured from the umbilical cord blood of 31 neonates, both full term and preterm. Birthweights and gestational ages were recorded.


RESULTS
PP IX levels in infants weighing < 1000 grams (n = 7) average 200 micrograms/dl, which is significantly higher than PP IX levels in infants weighing > 1000 grams (125 micrograms/dl, n = 24; P < 0.02).


CONCLUSIONS
Elevated PP IX levels may place preterm neonates at increased risk for photosensitizing retinal injury.
Bynoe
L A
LA
Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, Maryland 21205.
Gottsch
J D
JD
Sadda
S R
SR
Panton
R W
RW
Haller
E M
EM
Gleason
C A
CA
D005312:Fetal Blood / Q000737:chemistry; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D011524:Protoporphyrins / Q000097:blood*; D012178:Retinopathy of Prematurity / Q000209:etiology; D012307:Risk Factors; D014470:Umbilical Cord / Q000098:blood supply
D011524:Protoporphyrins; C028025:protoporphyrin IX