metabolic myopathy in thyrotoxicosis
Last reviewed 01/2018
The features of the myopathy associated with thyrotoxicosis include muscle weakness and wasting, often affecting the limb girdles, and normal creatinine kinase. In males, usually orientals, a rare form of hypokalaemic periodic paralysis occurs causing truncal and limb weakness.
Myasthenia gravis is associated with autoimmune thyroiditis and occasionally complicates hyperthyroidism; conversely, myasthenia gravis may be exacerbated by thyrotoxicosis.
The metabolic myopathy which may complicate Graves disease is caused by enlargement of the extraocular muscles due to infiltration with mucopolysaccharide, fat, inflammatory cells and eventually fibrosis.