Hypothyroid Myopathy Differential Diagnoses

Updated: May 28, 2020
  • Author: Divakara Kedlaya, MBBS; Chief Editor: Stephen Kishner, MD, MHA  more...
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Diagnostic Considerations

Myasthenia gravis

Myasthenia gravis has been associated with Graves disease and hypothyroidism. [37] Patients present with proximal muscle weakness that may be fatigable. Eventually, they can have dysphagia and respiratory distress.

Other metabolic, mitochondrial, and inflammatory myopathies

Glycogen metabolism deficiencies: These conditions are divided into dynamic and static deficiencies.

Dynamic myopathies: Manifestations of these disorders include exercise intolerance, pain, muscle cramps, and myoglobinuria.

  • Type V - Phosphorylase (McArdle disease)

  • Type VII - Phosphofructokinase (Tarui disease)

  • Type VIII - Phosphorylase B kinase

  • Type IX - Phosphoglycerate kinase

  • Type X - Phosphoglycerate mutase

  • Type XI - Lactate dehydrogenas

Static deficiencies: These disorders are associated with fixed weakness, but not with exercise intolerance or myoglobinuria.

  • Type II - Alpha-1,4 glucosidase (acid maltase)

  • Type III - Debranching

  • Type IV - Branching

Lipid metabolism deficiencies: These disorders can be accompanied by the following dynamic or static manifestations:

  • Carnitine palmitoyl transferase

  • Primary systemic/muscle carnitine deficiency

  • Secondary carnitine deficiency (eg, beta-oxidation defects, medications [such as valproic acid])

  • Purine metabolism deficiencies (eg, myoadenylate deaminase deficiency)

Mitochondrial myopathies

  • Pyruvate dehydrogenase complex deficiencies (eg, Leigh syndrome)

  • Progressive external ophthalmoplegia

  • Kearns-Sayre syndrome

  • Mitochondrial encephalopathy with lactic acidosis and strokelike episodes

  • Myoclonic epilepsy and ragged red fibers

  • Mitochondrial neurogastrointestinal encephalomyopathy

  • Mitochondrial depletion syndrome

  • Leigh syndrome and neuropathy, ataxia, or retinitis pigmentosa

  • Succinate dehydrogenase deficiency

Channelopathies are also differential diagnoses for myopathy.

Inflammatory myopathies are important differentials as well and may be difficult to differentiate from pure endocrine causes, including a heterogenous group of acquired, nonhereditary disorders characterized by muscle weakness and inflammation indicated by muscle biopsy.

Idiopathic inflammatory myopathies

  • Polymyositis

  • Dermatomyositis

  • Inclusion body myositis

  • Overlap syndromes with other connective tissue disease

  • Sarcoidosis and other granulomatous myositis conditions

  • Beh ç et syndrome

  • Inflammatory myopathies and eosinophilia

  • Focal myositis

  • Myositis ossificans

Bacterial infections

  • Staphylococcus aureus

  • Escherichia coli

  • Yersinia species

  • Legionella

  • Gas gangrene (Clostridium welchii)

  • Leprous myositis

  • Lyme disease

Viral infections

  • Acute influenza or other viral infections

  • Retrovirus-related myopathies (human immunodeficiency virus [HIV], human T-cell leukemia virus type 1)

  • Hepatitis B and C

  • Postpolio syndrome

Parasitic infections

  • Trichinosis

  • Toxoplasmosis

  • Cysticercosis

Fungal infections

  • Candida species

  • Cryptococcus species

  • Sporotrichosis species

Differential Diagnoses