Hypothyroid myopathy: A peculiar clinical presentation of thyroid failure. Review of the literature

Abstract

Abnormalities in thyroid function are common endocrine disorders that affect 5-10 % of the general population, with hypothyroidism occurring more frequently than hyperthyroidism. Clinical symptoms and signs are often nonspecific, particularly in hypothyroidism. Muscular symptoms (stiffness, myalgias, cramps, easy fatigability) are mentioned by the majority of patients with frank hypothyroidism. Often underestimated is the fact that muscle symptoms may represent the predominant or the only clinical manifestation of hypothyroidism, raising the issue of a differential diagnosis with other causes of myopathy, which sometimes can be difficult. Elevated serum creatine kinase, which not necessarily correlates with the severity of the myopathic symptoms, is certainly suggestive of muscle impairment, though it does not explain the cause. Rare muscular manifestations, associated with hypothyroidism, are rhabdomyolysis, acute compartment syndrome, Hoffman's syndrome and Kocher-Debré-Sémélaigne syndrome. Though the pathogenesis of hypothyroid myopathy is not entirely known, proposed mechanisms include altered glycogenolytic and oxidative metabolism, altered expression of contractile proteins, and neuro-mediated damage. Correlation studies of haplotype, muscle gene expression and protein characterization, could help understanding the pathophysiological mechanisms of this myopathic presentation of hypothyroidism.

A journey from brain to muscle across the thyroid continent

“…[2] before I realized that the abstract had already been published in PubMed! I have received further requests for the same article as well as for other articles [3][4][5] that appear in the present special issue while I had been attending the 86th Annual Meeting of the American Thyroid Association (ATA) in Denver, Colorado, this September. Two of these papers were even mentioned at the discussion of some posters between authors and attendees, and I was invited to provide some further information.…”

“…One might ask why this guest issue contains a number of articles that I myself have coauthored [3][4][5][6][7][8]. Here are the answers.…”

“…Let us allow some time to permit thyroid hormones to arrive to the skeletal muscles [5] and the intestine (10), and remain in the thyroid to see other things going on, things of autoimmune [3,7,9], neoplastic [6] or multifaceted nature [12].…”

“…Circulating thyroid hormones have arrived, at normal or low concentrations, into two target tissues: the skeletal muscles [5] and the intestine [10]. So, it is time to go give a look.…”

“…Underestimated is the fact that muscle symptoms may represent the predominant or the sole manifestation of hypothyroidism, raising the issue of a differential diagnosis with other causes of myopathy [5]. Rare muscular manifestations, associated with hypothyroidism, are rhabdomyolysis, acute compartment syndrome, Hoffman's syndrome and Kocher-Debré-Sémélaigne syndrome.…”