Multiple hormone resistance in short children born with intrauterine growth retardation?

Intrauterine growth retardation (IUGR) is encountered in 2.5% (-2 SD) of newborns. Lack of postnatal catch-up growth is found in 8-20%. If GH secretion is increased early postnatally in IUGR, then some persistently short IUGR children may present with GH insufficiency. However, the mechanism of postnatal catch-up growth is heterogenous. The response to GH treatment with regard to plasma IGF-1, GH dose and growth velocity was analyzed in persistently short idiopathic IUGR children and compared to GH-deficient (GHD) and familial short stature (FSS) children of similar age and degree of short stature. IUGR children require both a greater basal and GH-induced plasma IGF-1 in order to achieve a growth velocity of similar magnitude to that of FSS and GHD children. These data suggest a different sensitivity to GH in IUGR compared to FSS or GHD children, sustaining the hypothesis that these idiopathic IUGR children may be partially IGF-1 resistant. The recent report of partial insulin resistance in IUGR subjects raises the possibility of an IGF-1 receptor- or post-receptor-mediated defect.