Comparison of the growth-promoting effects of insulin-like growth factor I and growth hormone in the early years of life

Aims: Four infants with isolated growth hormone deficiency (IGHD) and five with Laron syndrome (LS) were studied. Birth length ranged from -2.5 to -4.5 SDS in both groups. Results: Untreated IGHD children decreased in length from -2.5 to -5.2 SDS at 1 y and to -5.7 SDS at 2 y. Human growth hormone (hGH) treatment (0.07 U/kg/d) increased height by 1.2-2.4 SDS in 3 y. Untreated children with LS decreased in length from -3.5 to -6.5 SDS. Insulin-like growth factor (IGF)-I treatment (150-200 μg/kg/d) in 3 LS patients increased height by 0.5-1.5 SDS in 3 y. All untreated infants had borderline or below normal head circumferences. Both treatments induced a rapid catch-up in head size. In the two untreated LS patients, head circumference remained subnormal. Conclusions: Despite similar birth length, infants with IGHD responded better to hGH in terms of linear growth than did infants with LS to IGF-I, whereas the response in brain growth was similar.