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.
Göteborg Pediatric Growth Research Center, Department of Pediatrics, Institute of the Health of Women and Children, Sweden. ann.hellstrom@medfak.gu.SE
Ann
A
Hellström
Eva
E
Engström
Anna-Lena
AL
Hård
Kerstin
K
Albertsson-Wikland
Björn
B
Carlsson
Aimon
A
Niklasson
Chatarina
C
Löfqvist
Elisabeth
E
Svensson
Sture
S
Holm
Uwe
U
Ewald
Gerd
G
Holmström
Lois E H
LE
Smith
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