Postnatal serum insulin-like growth factor I deficiency is associated with retinopathy of prematurity and other complications of premature birth.
OBJECTIVE
Insulin-like growth factor I (IGF-I) is necessary for normal development of retinal blood vessels in mice and humans. Because retinopathy of prematurity (ROP) is initiated by abnormal postnatal retinal development, we hypothesized that prolonged low IGF-I in premature infants might be a risk factor for ROP.


METHODS
We conducted a prospective, longitudinal study measuring serum IGF-I concentrations weekly in 84 premature infants from birth (postmenstrual ages: 24-32 weeks) until discharge from the hospital. Infants were evaluated for ROP and other morbidity of prematurity: bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and necrotizing enterocolitis (NEC).


RESULTS
Low serum IGF-I values correlated with later development of ROP. The mean IGF-I +/- SEM level during postmenstrual ages 30-33 weeks was lowest with severe ROP (25 +/- 2.41 micro g/L), 29 +/- 1.76 micro g/L with moderate ROP, and 33 +/- 1.72 micro g/L with no ROP. The duration of low IGF-I also correlated strongly with the severity of ROP. The interval from birth until serum IGF-I levels reached >33 micro g/L was 23 +/- 2.6 days for no ROP, 44 +/- 4.8 days for moderate ROP, and 52 +/- 7.5 days for severe ROP. Each adjusted stepwise increase of 5 micro g/L in mean IGF-I during postmenstrual ages 30 to 33 weeks decreased the risk of proliferative ROP by 45%. Other complications (NEC, BPD, IVH) were correlated with ROP and with low IGF-I levels. The relative risk for any morbidity (ROP, BPD, IVH, or NEC) was increased 2.2-fold (95% confidence interval: 1.41-3.43) if IGF-I was <or=33 micro g/L at 33 weeks' postmenstrual age.


CONCLUSIONS
These results indicate that persistent low serum concentrations of IGF-I after premature birth are associated with later development of ROP and other complications of prematurity. IGF-I is at least as strong a determinant of risk for ROP as postmenstrual age at birth and birth weight.
Hellström
Ann
A
Göteborg Pediatric Growth Research Center, Department of Pediatrics, Institute of the Health of Women and Children, Sweden. ann.hellstrom@medfak.gu.SE
Engström
Eva
E
Hård
Anna-Lena
AL
Albertsson-Wikland
Kerstin
K
Carlsson
Björn
B
Niklasson
Aimon
A
Löfqvist
Chatarina
C
Svensson
Elisabeth
E
Holm
Sture
S
Ewald
Uwe
U
Holmström
Gerd
G
Smith
Lois E H
LE
D001724:Birth Weight; D001997:Bronchopulmonary Dysplasia / Q000097:blood / Q000453:epidemiology; D002543:Cerebral Hemorrhage / Q000097:blood / Q000453:epidemiology; D020345:Enterocolitis, Necrotizing / Q000097:blood / Q000453:epidemiology; D005317:Fetal Growth Retardation / Q000097:blood; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000172:deficiency*; D008137:Longitudinal Studies; D011446:Prospective Studies; D012178:Retinopathy of Prematurity / Q000097:blood* / Q000453:epidemiology; D012307:Risk Factors; D012720:Severity of Illness Index; D013548:Sweden / Q000453:epidemiology
D007334:Insulin-Like Growth Factor I