Bone metabolism and circulating IGF-I and IGFBPs in dexamethasone-treated preterm infants

• Published in: Early human development 1999-12, Vol.56 (2-3), p.127-141
• Main Authors: Ward, Wendy E., Atkinson, Stephanie A., Donovan, Sharon M., Paes, Bosco
• Format: Article
• Language: English
• Subjects: Absorptiometry, Photon; Biological and medical sciences; Body Composition; Bone; Bone and Bones - metabolism; Bone Density; Bronchopulmonary dysplasia; Collagen - urine; Collagen Type I; Dexamethasone; Dexamethasone - therapeutic use; Female; Fundamental and applied biological sciences. Psychology; Gestational Age; Glucocorticoids - therapeutic use; Humans; IGF-I; Infant, Newborn; Infant, Premature - metabolism; Insulin-Like Growth Factor Binding Protein 2 - blood; Insulin-Like Growth Factor Binding Protein 3 - blood; Insulin-Like Growth Factor Binding Proteins - blood; Insulin-Like Growth Factor I - metabolism; Male; Metabolisms and neurohumoral controls; Milk, Human; Nitrogen metabolism. Proteins. Glycoproteins. Nucleic acids. Collagen; Osteocalcin - blood; Peptides - urine; Premature infants; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0378-3782; 1872-6232
• DOI: 10.1016/S0378-3782(99)00039-0

Aim: To characterize the ontogeny of circulating IGF-I, the IGF binding proteins (IGFBPs) and biochemical markers of bone turnover in dexamethasone (DEX)-treated preterm infants with chronic lung disease. Methods: Plasma and urine samples from 17 infants were obtained prior to DEX, after 9–12 days of DEX and 10 days after the completion of DEX to assess plasma IGF-I, IGFBPs, osteocalcin and urinary N-telopeptide. Nutrient intakes and growth were monitored from birth until term corrected age at which time body composition was evaluated by dual energy X-ray absorptiometry. Results: Although nutrient intakes did not differ during or after DEX, weight gain (115 vs. 174 g/week) and length gain (0.7 vs. 1.0 cm/week) were higher after DEX treatment. Plasma IGF-I, IGFBP-3 and osteocalcin increased over time. N-telopeptide was the only biochemical parameter which appeared to be suppressed during DEX (1342 nM bone collagen equivalents/mM creatinine vs. 2486 (pre-DEX) and 2292 (post-DEX)). At term corrected age, bone mineral content was lower in dexamethasone-treated infants compared to preterm and term reference infants. Conclusion: Changes in circulating IGFBP-2 and IGFBP-3 paralleled the changes reported in non-steroid-treated infants; however, it remains uncertain whether the natural rise in IGF-I was suppressed by DEX treatment. Assessment of these circulating components provided limited insight into the mechanisms by which DEX alters growth and bone turnover.