Muscle Weakness in Thyroid Disease: When It Is Not Thyrotoxic Myopathy?
https://doi.org/10.15605/jafes.041.S1
- Author:
Hamizah Hamzah
1
;
Sarojini Devi Simanchalam
1
;
Yap Yon Lek
2
;
Wong Poh Shean
1
;
Nor Afidah Karim
1
;
Nadiah Mohd Noor
1
;
Noor Lita Adam
1
Author Information
1. Endocrinology Unit, Department of Medicine, Hospital Tuanku Ja’afar Seremban
2. Rheumatology Unit, Department of Medicine, Hospital Tuanku Ja’afar Seremban
- Publication Type:Journal Article
- MeSH:
Muscle Weakness;
Thyroid Diseases;
Muscular Diseases
- From:
Journal of the ASEAN Federation of Endocrine Societies
2026;41(S1):107-108
- CountryPhilippines
- Language:English
-
Abstract:
Introduction:Muscle weakness in thyroid disease is commonly attributed
to thyrotoxic myopathy or hypokalemic periodic paralysis.
Nevertheless, autoimmune conditions such as idiopathic
inflammatory myopathies (IIM) and myasthenia gravis
(MG) should be considered, as they may coexist with
Graves’ disease.
Case:A 54-year-old female with hypertension and Graves’
disease, treated with carbimazole for 2 years, had her
therapy discontinued after remission. She was restarted
on low-dose carbimazole following symptom recurrence.
Three weeks later, she developed progressive proximal
weakness, dysphagia, hoarseness, anorexia, and weight
loss. On examination, body mass index was 22 kg/m²
with mild proptosis, symmetrical proximal weakness
(MRC 4/5), and erythematous rashes on thighs and shins.
Otorhinolaryngology evaluation confirmed bilateral vocal cord palsy. Investigations revealed markedly elevated
creatine kinase (7,950 U/L), aspartate aminotransferase
(349 U/L), and alanine aminotransferase (179 U/L), with
euthyroid biochemistry (thyroid-stimulating hormone
5.21 mIU/L, free thyroxine 4 16.6 pmol/L). Hypokalemia
correction failed to improve symptoms, excluding periodic
paralysis. ANA, C3, and C4 were normal. Myositis panel
showed strong anti-Cytosolic 5’-nucleotidase 1A positivity
with borderline anti-Ro-52. A diagnosis of IIM with bulbar
involvement was made. She was treated with intravenous
methylprednisolone and intravenous immunoglobulin,
with clinical improvement.
Conclusion:This case highlights the diagnostic challenge of muscle
weakness in thyroid disease. While thyrotoxic myopathy is
often presumed, markedly elevated creatinine kinase, rash,
and bulbar involvement should prompt suspicion of IIM.
Early immunosuppressive therapy is essential to achieve
favorable outcomes.
- Full text:2026080508214522919EP_A158.pdf
