Published in:
Open Access 01-12-2015 | Research article
Growth hormone (GH) dose-dependent IGF-I response relates to pubertal height gain
Published in: BMC Endocrine Disorders | Issue 1/2015
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Background
Responsiveness to GH treatment can be estimated by both growth and ∆IGF-I. The primary aim of the present study was to investigate if mimicking the physiological increase during puberty in GH secretion, by using a higher GH dose could lead to pubertal IGFs in short children with low GH secretion. The secondary aim was to explore the relationship between IGF-I, IGFBP-3 and the IGF-I/IGFBP-3 ratio and gain in height.
Methods
A multicentre, randomized, clinical trial (TRN88-177) in 104 children (90 boys), who had received GH 33 μg/kg/day during at least 1 prepubertal year. They were followed from GH start to adult height (mean, 7.5 years; range, 4.6–10.7). At onset of puberty, children were randomized into three groups, to receive 67 μg/kg/day (GH67) given once (GH67x1; n = 30) or divided into two daily injection (GH33x2; n = 36), or to remain on a single 33 μg/kg/day dose (GH33x1; n = 38). The outcome measures were change and obtained mean on-treatment IGF-ISDS, IGFBP3SDS and IGF-I/IGFBP3 ratioSDS during prepuberty and puberty. These variables were assessed in relation to prepubertal, pubertal and total gain in heightSDS.
Results
Mean prepubertal increases 1 year after GH start were: 2.1 IGF-ISDS, 0.6 IGFBP3SDS and 1.5 IGF-I/IGFBP3ratioSDS. A significant positive correlation was found between prepubertal ∆IGFs and both prepubertal and total gain in heightSDS. During puberty changes in IGFs were GH dose-dependent: mean pubertal level of IGF-ISDS was higher in GH67 vs GH33 (p = 0.031). First year pubertal ∆IGF-ISDS was significantly higher in the GH67vs GH33 group (0.5 vs −0.1, respectively, p = 0.007), as well as ∆IGF-ISDS to the pubertal mean level (0.2 vs −0.2, p = 0.028). In multivariate analyses, the prepubertal increase in ‘∆IGF-ISDS from GH start’ and the ‘GH dose-dependent pubertal ∆IGF-ISDS’ were the most important variables for explaining variation in prepubertal (21 %), pubertal (26 %) and total (28 %) gain in heightSDS.
Trial registration
TRN 88–177, not applicable 1988.
Conclusion
The dose-dependent change in IGFs was related to a dose-dependent pubertal gain in heightSDS. The attempt to mimic normal physiology by giving a higher GH dose during puberty was associated with both an increase in IGF-I and a dose-dependent gain in heightSDS.