Abstract
Neuromuscular disorders can arise in the context of various endocrine dysfunctions and, in some cases, represent the first clinical manifestation leading to diagnosis. An underlying endocrine cause should be considered in patients presenting with myalgia, cramps, muscle weakness, fatigue, or muscle atrophy/hypertrophy, particularly when symptoms are persistent or acutely worsening. This review covers six major categories of endocrine myopathy: (1) thyroid dysfunction (hyperthyroidism, hypothyroidism, thyrotoxic periodic paralysis); (2) parathyroid disorders and vitamin D deficiency (hyperparathyroidism, hypoparathyroidism, osteomalacia); (3) adrenal disorders (Cushing's syndrome, primary hyperaldosteronism, adrenal insufficiency/Addison's disease); (4) pituitary disease (acromegaly, hypopituitarism); (5) androgen deficiency; and (6) diabetes mellitus. Common features across these conditions include proximal limb weakness, relatively mild histological abnormalities despite severe clinical presentation, and favorable response to treatment of the underlying endocrinopathy. CK levels and muscle biopsy findings vary by etiology. Most cases do not require extensive investigations (muscle biopsy, electrophysiological studies, genetic testing) unless the presentation is atypical or fails to improve with hormonal treatment. The authors conclude that patients on glucocorticoids or statins should be regularly assessed for muscle weakness, as endocrine myopathies are frequently misdiagnosed and mismanaged as inflammatory myopathies.
