Spontaneous growth hormone secretion and IGF1:IGFBP3 molar ratios in children born small for gestational age (SGA)

Abstract

Objective. To analyze spontaneous nocturnal GH profiles, IGF1 and IGFBP3 serum levels, as well as IGF1:IGFBP3 molar ratios in SGA children without postnatal catch-up growth. Methods. Short statured prepubertal SGA children ( n = 24) were matched retrospectively for sex, age and BMI to short statured children born appropriate for gestational age (AGA), who underwent the same diagnostic program. GH deficiency was excluded in all children by a normal increase of GH in 2 stimulation tests (>8 μg/L). For assessment of spontaneous nocturnal GH secretion, GH serum levels were measured every 20 min for 10 h. Pulsatility was analyzed with Pulsar. Results. None of the Pulsar derived descriptive parameters showed a significant difference between SGA and AGA children. Overall, median IGF1 levels were approximately one SDS below zero SDS ( p < 0.001), whereas IGFBP3 levels were normal in both groups. Thus, the IGF1:IGFBP3 molar ratios were significantly lower from zero ( p < 0.01) in SGA as well as in AGA children. However, IGF1- and IGFBP3-SDS levels related either to chronological or to bone age did not differ significantly between SGA and AGA children. Conclusions. Building matched pairs of short statured children born either SGA or AGA for sex, age and BMI we did not find any significant differences in spontaneous nocturnal GH secretion, IGF1, IGFBP3, and IGF1:IGFBP3 molar ratios.