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Context About 30% of patients with active acromegaly experience paradoxically increased growth hormone (GH) secretion during the diagnostic oral glucose tolerance test (OGTT). Endogenous glucose-dependent insulinotropic polypeptide (GIP) is implicated in this paradoxical secretion. Objective We used the GIP receptor (GIPR) antagonist GIP(3-30)NH2 to test the hypothesis that GIP mediates this paradoxical response when GIPR is abundantly expressed in somatotropinomas. Methods A total of 25 treatment-naive patients with acromegaly were enrolled. Each patient underwent one OGTT during simultaneous placebo infusion and one OGTT during a GIP(3-30)NH2 infusion. Blood samples were drawn at baseline and regularly after infusions to measure GH. We assessed pituitary adenoma size by magnetic resonance imaging and GIPR expression by immunohistochemistry on resected somatotropinomas. For mechanistic confirmation, we applied in vitro and ex vivo approaches. The main outcome measure was the effect of GIP(3-30)NH2 on paradoxical GH secretion during OGTT as a measure of GIP involvement. Results In 4 of 7 patients with paradoxical GH secretion, GIP(3-30)NH2 infusion completely abolished the paradoxical response (P =.0003). Somatotrophs were available from 3 of 4 of these patients, all showing abundant GIPR expression. Adenoma size did not differ between patients with and without paradoxical GH secretion. Conclusion Of 25 patients with acromegaly, 7 had paradoxical GH secretion during OGTT, and pharmaceutical GIPR blockade abolished this secretion in 4. Corresponding somatotroph adenomas abundantly expressed GIPR, suggesting a therapeutic target in this subpopulation of patients. In vitro and ex vivo analyses confirmed the role of GIP and the effects of the antagonist. [ABSTRACT FROM AUTHOR]

Objective: Acromegaly is associated with increased morbidity and mortality if left untreated. The therapeutic options include surgery, medical treatment, and radiotherapy. Several guidelines and recommendations on treatment algorithms and follow‐up exist. However, not all recommendations are strictly evidence‐based. To evaluate consensus on the treatment and follow‐up of patients with acromegaly in the Nordic countries. Methods: A Delphi process was used to map the landscape of acromegaly management in Denmark, Sweden, Norway, Finland, and Iceland. An expert panel developed 37 statements on the treatment and follow‐up of patients with acromegaly. Dedicated endocrinologists (n = 47) from the Nordic countries were invited to rate their extent of agreement with the statements, using a Likert‐type scale (1−7). Consensus was defined as ≥80% of panelists rating their agreement as ≥5 or ≤3 on the Likert‐type scale. Results: Consensus was reached in 41% (15/37) of the statements. Panelists agreed that pituitary surgery remains first line treatment. There was general agreement to recommend first‐generation somatostatin analog (SSA) treatment after failed surgery and to consider repeat surgery. In addition, there was agreement to recommend combination therapy with first‐generation SSA and pegvisomant as second‐ or third‐line treatment. In more than 50% of the statements, consensus was not achieved. Considerable disagreement existed regarding pegvisomant monotherapy, and treatment with pasireotide and dopamine agonists. Conclusion: This consensus exploration study on the management of patients with acromegaly in the Nordic countries revealed a relatively large degree of disagreement among experts, which mirrors the complexity of the disease and the shortage of evidence‐based data. [ABSTRACT FROM AUTHOR]

Background: Active acromegaly is characterized by increased lean body mass, but the mechanisms underlying the protein anabolic effect are unclear. Aim: To study if active acromegaly induces reversible changes in whole-body and skeletal muscle protein kinetics. Patients and Methods: Eighteen patients with acromegaly were investigated before and 47 ± 10 weeks after disease control by surgery (n = 8) and/or medical treatment (n = 10). Labeled phenylalanine and tyrosine tracers were employed to assess whole-body and regional forearm muscle protein kinetics. Intramyocellular protein signaling was assessed in skeletal muscle biopsies, and whole-body dual-energy X-ray absorptiometry scan and indirect calorimetry assessed lean body mass (LBM) and resting energy expenditure, respectively. Results: Disease control induced a 7% decrease in lean body mass (P < .000) and a 14% decrease in LBM-adjusted energy expenditure. Wholebody phenylalanine breakdown decreased after disease control (P = .005) accompanied by a decrease in the degradation of phenylalanine to tyrosine (P = .005) and a decrease in whole-body phenylalanine synthesis (P = .030). Skeletal muscle protein synthesis tended to decrease after disease control (P = .122), whereas the muscle protein breakdown (P = .437) and muscle protein loss were unaltered (P = .371). Unc-51 like autophagy activating kinase 1 phosphorylation, an activator of protein breakdown, increased after disease control (P = .042). Conclusions: Active acromegaly represents a reversible high flux state in which both whole-body protein breakdown and synthesis are increased, whereas forearm muscle protein kinetics are unaltered. Future studies are needed to decipher the link between protein kinetics and the structure and function of the associated growth hormone-induced increase in lean body mass. [ABSTRACT FROM AUTHOR]

Objectives: Insulin resistance is associated with ectopic lipid deposition. Growth hormone (GH) status also modulates ectopic lipid accumulation, but how this associates with insulin resistance in patients with GH disorders is not well established. Design and Methods: Twenty-one patients diagnosed with acromegaly and 12 patients with adult GH deficiency (GHD) were studied at diagnosis and after treatment. A reference group of 12 subjects was included. Each study day comprised assessment of body composition with dual-energy X-ray absorptiometry, ectopic lipid deposition in the liver by MR spectroscopy, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Results: Disease control of acromegaly decreased lean body mass (LBM) (P< .000) and increased the percentage of total body fat (TBF) (P<.000). GH replacement increased LBM in the GHD patients (P=.007) and decreased the percentage of TBF (P=.010). The intrahepatic lipid (IHL) content increased after disease control in acromegaly (P=.004), whereas IHL did not change significantly after GH replacement in GHD (P=.34). Insulin resistance (HOMA-IR) improved after disease control of acromegaly (P<.000) and remained unaltered after GH replacement in the GHD patients (P=.829). Conclusions: 1) GH status is a significant modulator of body composition and insulin sensitivity. 2) GH excess reduces total fat mass and intrahepatic lipid content together with induction of insulin resistance. 3) The data support the notion that GH-induced insulin resistance is unassociated with hepatic lipid accumulation. [ABSTRACT FROM AUTHOR]