Response to IGF-1 Generation Test in Short Prepubertal Children Born Very Preterm or at Term.
OBJECTIVE
To investigate whether short children born very preterm (<32 weeks of gestation) exhibit features of growth hormone (GH) resistance compared to term peers.


METHODS
We studied 26 prepubertal children (aged 7.0 ± 2.0 years) with short stature (height adjusted for parents' heights <10th percentile), who were born appropriate for gestational age and either very preterm (n = 11) or at term (n = 15). Children underwent insulin-like growth factor-1 (IGF-1) generation test via a daily recombinant human GH (rhGH) dose (0.05 mg/kg/day) over 4 consecutive days. Hormone and binding proteins were measured at baseline and day 5.


RESULTS
At baseline, preterm children had lower IGF-binding protein 1 (IGFBP-1; -22%; p = 0.049) and IGFBP-3 (-24%; p = 0.013) concentrations than term children. Preterm children also had insulin concentrations that tended to be 39% higher (p = 0.059) than term peers. After stimulation, IGF-1 and IGFBP-3 concentrations increased similarly in term and preterm groups, while GH-binding protein (GHBP) concentrations decreased in both groups. Preterm children had higher GHBP (+50%; p = 0.049), insulin (+86%; p = 0.005), and leptin (+107%; p = 0.020) but lower IGFBP-1 (-47%; p = 0.006) concentrations than term children following rhGH stimulation.


CONCLUSIONS
Preterm children who are short for genetic height potential show no evidence of GH resistance that would explain their short stature. However, there was indirect evidence of insulin resistance in the preterm children, as previously described in this group.
Liggins Institute, University of Auckland, Auckland, New Zealand.
Harriet L
HL
Miles
José G B
JG
Derraik
Valentina
V
Chiavaroli
Paul L
PL
Hofman
Wayne S
WS
Cutfield
D001827:Body Height; D002352:Carrier Proteins; D002648:Child; D005260:Female; D006130:Growth Disorders / Q000175:diagnosis*; D019382:Human Growth Hormone / Q000494:pharmacology; D006801:Humans; D062071:Infant, Extremely Premature / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D020738:Leptin / Q000097:blood; D008297:Male; D011994:Recombinant Proteins / Q000494:pharmacology
D002352:Carrier Proteins; C583557:IGF1 protein, human; D007328:Insulin; D018972:Insulin-Like Growth Factor Binding Protein 3; D020738:Leptin; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; C051815:somatotropin-binding protein