Cited by 71Thyroid Disorders and TreatmentsMuscle metabolism and nutritionMuscle Physiology and Disorders

Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown

Riis, Anne Lene Dalkjær, Jørgensen, Jens Otto Lunde, Gjedde, Signe, Nørrelund, Helene, Jurik, Anne Grethe, Nair, K. S., Ivarsen, Per, Weeke, Jørgen +1 more·2005·American Journal of Physiology-Endocrinology and Metabolism

Abstract

Thyroid hormones have significant metabolic effects, and muscle wasting and weakness are prominent clinical features of chronic hyperthyroidism. To assess the underlying mechanisms, we examined seven hyperthyroid women with Graves' disease before (Ht) and after (Eut) medical treatment and seven control subjects (Ctr). All subjects underwent a 3-h study in the postabsorptive state. After regional catheterization, protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique using [ 15 N]phenylalanine and [ 2 H 4] tyrosine. Before treatment, triiodothyronine was elevated (6.6 nmol/l) and whole body protein breakdown was icreased 40%. The net forearm release of phenylalanine was increased in hyperthyroidism (μg·100 ml −1 ·min −1 ): −7.0 ± 1.2 Ht vs. −3.8 ± 0.8 Eut ( P = 0.04), −4.2 ± 0.3 Ctr ( P = 0.048). Muscle protein breakdown, assessed by phenylalanine rate of appearance, was increased (μg·100 ml −1 ·min −1 ): 15.5 ± 2.0 Ht vs. 9.6 ± 1.4 Eut ( P = 0.03), 9.9 ± 0.6 Ctr ( P = 0.02). Muscle protein synthesis rate did not differ significantly. Muscle mass and muscle function were decreased 10–20% before treatment. All abnormalities were normalized after therapy. In conclusion, our results show that hyperthyroidism is associated with increased muscle amino acid release resulting from increased muscle protein breakdown. These abnormalities can explain the clinical manifestations of sarcopenia and myopathy.

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Crossref · 10.1152/ajpendo.00253.2004

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Authors
Riis, A. L. D., Jørgensen, J. O. L., Gjedde, S., Nørrelund, H., Jurik, A. G., Nair, K. S., Ivarsen, P., Weeke, J., & Møller, N.
Affiliations
  • Aarhus University Hospital (DK)
  • Aarhus University (DK)
  • Mayo Clinic (US)
Venue
American Journal of Physiology-Endocrinology and Metabolism
Published
2005-06
Volume
288
Issue
6
Pages
E1067-E1073
ISSN
  • 0193-1849 (ISSN-L)
  • 1522-1555
OpenAlex
W1972903285
Cited by
71
References
44
Citations by year
2026: 5 · 2025: 4 · 2024: 6 · 2023: 1 · 2022: 5 · 2021: 4 · 2020: 5 · 2019: 2 · 2018: 2 · 2016: 7 · 2014: 8 · 2013: 3 · 2012: 1
FWCI
2.48
Type
journal article
Language
en
Open access
closed
Locations
  • American Journal of Physiology-Endocrinology and Metabolism (publishedVersion)
  • PubMed (publishedVersion)
Funders
Aarhus Universitet
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
Keywords
hyperthyroidism, Graves' disease, muscle protein degradation, muscle protein synthesis, sarcopenia, myopathy, muscle atrophy, phenylalanine kinetics, triiodothyronine, forearm muscles
MeSH terms
Adult, Body Composition, Female, Forearm, Humans, Hyperthyroidism, Kinetics, Methimazole, Middle Aged, Muscle Proteins, Nitrogen Isotopes, Phenylalanine, Antithyroid Agents, Thyroid Hormones, Muscle, Skeletal

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