Metabolic Impact of Adult-Onset, Isolated, Growth Hormone Deficiency (AOiGHD) Due to Destruction of Pituitary Somatotropes

Growth hormone (GH) inhibits fat accumulation and promotes protein accretion, therefore the fall in GH observed with weight gain and normal aging may contribute to metabolic dysfunction. To directly test this hypothesis a novel mouse model of adult onset-isolated GH deficiency (AOiGHD) was generated by cross breeding rat GH promoter-driven Cre recombinase mice (Cre) with inducible diphtheria toxin receptor mice (iDTR) and treating adult Cre+/−,iDTR+/− offspring with DT to selectively destroy the somatotrope population of the anterior pituitary gland, leading to a reduction in circulating GH and IGF-I levels. DT-treated Cre−/−,iDTR+/− mice were used as GH-intact controls. AOiGHD improved whole body insulin sensitivity in both low-fat and high-fat fed mice. Consistent with improved insulin sensitivity, indirect calorimetry revealed AOiGHD mice preferentially utilized carbohydrates for energy metabolism, as compared to GH-intact controls. In high-fat, but not low-fat fed AOiGHD mice, fat mass increased, hepatic lipids decreased and glucose clearance and insulin output were impaired. These results suggest the age-related decline in GH helps to preserve systemic insulin sensitivity, and in the context of moderate caloric intake, prevents the deterioration in metabolic function. However, in the context of excess caloric intake, low GH leads to impaired insulin output, and thereby could contribute to the development of diabetes

Long-term safety of growth hormone in adults with growth hormone deficiency: Overview of 15,809 GH-treated patients.

CONTEXT: Data on long-term safety of growth hormone (GH) replacement in adults with GH deficiency (GHD) are needed. OBJECTIVE: To evaluate the safety of GH in the full KIMS (Pfizer International Metabolic Database) cohort. DESIGN, PATIENTS, SETTING, AND INTERVENTION: The worldwide, observational KIMS study included adults and adolescents with confirmed GHD. Patients were treated with GH (Genotropin ® [somatropin]; Pfizer, NY) and followed through routine clinical practice. MAIN OUTCOME MEASURES: Adverse events (AEs) and clinical characteristics (e.g., lipid profile, glucose) were collected. RESULTS: 15,809 GH-treated patients were analyzed (mean follow up of 5.3 years). AEs were reported in 51.2% of patients (treatment-related in 18.8%). Crude AE rate was higher in patients who were older, had GHD due to pituitary/hypothalamic tumors, or adult-onset GHD. AE rate analysis adjusted for age, gender, etiology, and follow-up time showed no correlation with GH dose. 606 deaths (3.8%) were reported (146 by neoplasms, 71 by cardiac/vascular disorders, 48 by cerebrovascular disorders). Overall de novo cancer incidence was comparable to that in the general population (standard incidence ratio 0.92; 95% CI 0.83-1.01). De novo cancer risk was significantly lower in patients with idiopathic/congenital GHD (0.64; 0.43-0.91), but similar in those with pituitary/hypothalamic tumors or other etiologies versus the general population. Neither adult-onset nor childhood-onset GHD was associated with increased de novo cancer risks. Neutral effects were observed in lipids/fasting blood glucose levels. CONCLUSIONS: These final KIMS cohort data support the safety of long-term GH replacement in adults with GHD as prescribed in routine clinical practice

Macimorelin as a Diagnostic Test for Adult GH Deficiency

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