Reduced fibroblast growth factor 21 and ß-Klotho secretion in untreated congenital isolated GH deficiency.

PURPOSES: Increasing evidence suggests that the FGF-Klotho endocrine system and the somatotropic system (pituitary and extra-pituitary GH) may have important metabolic and immune relationships, thus contributing to the pathophysiology of aging-related disorders, including diabetes, atherosclerosis, and cancer. The status of these interactions in isolated GH deficiency (IGHD) is unknown. The objective of this study was to assess the response of both FGF21 and ß-Klotho levels to a standard meal in a homogeneous group of adults with congenital untreated IGHD due to a homozygous mutation in the GHRH receptor gene. METHODS: In a cross-sectional study, we measured the levels of FGF21 and ß-Klotho, before and 30, 60, 120, and 180 min after a standardized test meal in 20 (11 males) IGHD and 20 (11 males) age-matched controls. Areas under the curves (AUC) of FGF21 and ß-Klotho were calculated. RESULTS: Baseline levels of FGF21 were similar, but baseline levels of ß-Klotho were lower in IGHD subjects. The IGHD individuals exhibited lower AUC for FGF21 and ß-Klotho levels than control subjects. There was a positive correlation between IGF1 and ß-Klotho levels in the pooled groups. No correlation was found between IGF1 and FGF21 levels. CONCLUSIONS: Subjects with lifetime, untreated IGHD exhibit reduced FGF21 and ß-Klotho levels response to a mixed meal. This difference may have consequences on metabolism and aging.

Enteroendocrine Connections in Congenital Isolated GH Deficiency Due to a GHRH Receptor Gene Mutation.

CONTEXT: GH and IGF-1 are crucial for attainment of normal body size and regulation of food intake, nutrient storage, and insulin sensitivity. Enteroendocrine connections exist between the GH-IGF-1 axis and insulin, ghrelin, and glucagon-like peptide 1 (GLP-1). The status of these connections in GH deficiency (GHD) is unknown. OBJECTIVE: To study the enteroendocrine connections before and after a standard meal test in a homogeneous population of adults with congenital untreated isolated GHD (IGHD) due to a mutation in the GHRH receptor gene. DESIGN: In a cross-sectional study of 20 individuals with IGHD and 20 control subjects, we measured glucose, insulin, ghrelin, and GLP-1 before and 30, 60, 120, and 180 minutes after a standardized test meal. Homeostasis model assessment index of insulin resistance (HOMA-IR) and homeostasis model assessment (HOMA)-ß were calculated. Participants scored feelings of hunger, fullness, and prospective food consumption on a visual analog scale. MAIN OUTCOME MEASURES: Area under the curve (AUC) values of glucose, insulin, ghrelin, GLP-1, hunger, fullness, and prospective food consumption. RESULTS: Fasting HOMA-IR and HOMA-ß were lower in individuals with IGHD than in control subjects (P = 0.002 and P = 0.023, respectively). AUC was higher for hunger (P < 0.0001), glucose (P = 0.0157), ghrelin (P < 0.0001), and GLP-1 (P < 0.0001) and smaller for fullness (P < 0.0001) in individuals with IGHD compared with control subjects. There was no difference in AUC for prospective food consumption or insulin. CONCLUSIONS: Untreated IGHD is associated with increased GLP-1 secretion and reduced postprandial ghrelin and hunger attenuation in response to a mixed meal. These enteroendocrine connections can result in a favorable outcome in terms of environmental adaptation and guaranteeing appropriate food intake and can confer metabolic benefits.