Relationship Between the Serum FGF21 Level and Growth in Children of Short Stature

Background: This study investigated the relationship between fibroblast growth factor 21 (FGF21) levels and growth in children with growth hormone deficiency (GHD) and idiopathic short stature (ISS), and the effects of the FGF21 level on response to growth hormone (GH) treatment. Methods: We included 171 pre-pubertal children with a GHD (n = 54), ISS (n = 46), and normal height (n = 71). Fasting FGF21 levels were measured at baseline and every 6 months during GH treatment. Factors associated with growth velocity (GV) after GH therapy were investigated. Results: The FGF21 level was higher in short children than in the controls without significant difference between the GHD and ISS groups. In the GHD group, the FGF21 level was inversely associated with the free fatty acid (FFA) level at baseline (r = -0.28, P = 0.039), however, was positively correlated with the FFA level at 12 months (r = 0.62, P = 0.016). The GV over 12 months of GH therapy was positively associated with the delta insulin-like growth factor 1 level (8 = 0.003, P = 0.020). The baseline log-transformed FGF21 level was inversely associated with GV with marginal significance (8 = -0.64, P = 0.070). Conclusion: The FGF21 level was higher in children of short stature, both those with GHD and the ISS, than in children with normal growth. The pretreatment FGF21 level negatively affected the GV of children with GH-treated GHD. These results suggest the existence of a GH/FFA/FGF21 axis in children.