Serum insulin-like growth Factor-I (IGF-I) and IGF binding protein-3 (IGFBP3) in growing preterm infants on enteral nutrition

We analyzed the range of serum concentrations of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) and their inter-relationships with age and some parameters of nutritional and hormonal status in 46 growing preterm infants on enteral nutrition, 72 nutritional balances were performed, with a cross-sectional study design, at a mean age of 35.3 ± 17.2 days, equivalent to a mean corrected age (gestational + postnatal age) of 36 ± 2.3 weeks. Serum concentrations of IGF-I (mean 64 ± 36 ng/ml) and IGFBP-3 (mean 1.15 ± 0.53 mg/l) correlated significantly with each other (r=0.46) and both correlated with body weight (r=0.43 and 0.34), body length (r=0.44 and 0.36) and serum concentrations of prealbumin, apolipoprotein A and cholesterol, IGF-I also correlated with urinary excretion of C-peptide (r=0.32). There was a weak correlation between IGFBIP3 and postnatal age (r= 0.36) but no correlation between IGF-I and IGFBP-3 and corrected age or urinary excretion of growth hormone. In growing preterm infants, at least until 40 weeks of corrected age, serum concentrations of IGF-I and IGFBPS seem to be related principally to body weight, body length and nutritional factors, but not to growth hormone.