Whole-body and forearm muscle protein metabolism in patients with acromegaly before and after treatment

Mai C. Arlien-Søborg*, Jakob Dal, Michael Alle Madsen, Morten Lyng Høgild, Steen B. Pedersen, Niels Jessen, Jens O. L. Jørgensen, Niels Møller

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

1 Citation (Scopus)


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. Whole-body 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.

Original languageEnglish
Article numberdgad190
JournalJournal of Clinical Endocrinology and Metabolism
Issue number9
Pages (from-to)e671-e678
Number of pages8
Publication statusPublished - 1 Sept 2023

Bibliographical note

© The Author(s) 2023. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


  • Acromegaly/therapy
  • Body Composition/physiology
  • Energy Metabolism/physiology
  • Forearm
  • Humans
  • Muscle Proteins/metabolism
  • Muscle, Skeletal/metabolism
  • Phenylalanine
  • Tyrosine
  • protein kinetics
  • protein metabolism
  • body composition
  • acromegaly
  • growth hormone


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