Circulating FGF19 and FGF21 surge in early infancy from infra- to supra-adult concentrations

BACKGROUND/OBJECTIVE: Fibroblast growth factor 19 (FGF19) and 21 (FGF21) have been linked to obesity and type 2 diabetes in adults. We assessed the circulating concentrations of these factors in human neonates and infants, and their association with the endocrine-metabolic changes associated to prenatal growth restraint. SUBJECTS/METHODS: Circulating FGF19 and FGF21, selected hormones (insulin, insulin-like growth factor I and high- molecular-weight (HMW) adiponectin) and body composition (absorptiometry) were assessed longitudinally in 44 infants born appropriate( AGA) or small-for-gestational-age (SGA). Measurements were performed at 0, 4 and 12 months in AGA infants; at 0 and 4 months in SGA infants; and cross-sectionally in 11 first-week AGA newborns. RESULTS: Circulating FGF19 and FGF21 surged >10-fold in early infancy from infra- to supra-adult concentrations, the FGF19 surge appearing slower and more pronounced than the FGF21 surge. Whereas the FGF21 surge was of similar magnitude in AGA and SGA infants, FGF19 induction was significantly reduced in SGA infants. In AGA and SGA infants, cord-blood FGF21 and serum FGF19 at 4 months showed a positive correlation with HMW adiponectin (r = 0.49, P = 0.013; r = 0.43, P = 0.019, respectively). CONCLUSIONS: Our results suggest that these early FGF19 and FGF21 surges are of a physiological relevance that warrants further delineation and that may extend beyond infancy.