Endocrine myopathies: clinical and histopathological features of the major forms

Abstract

Endocrinopathies, such as thyroid and parathyroid diseases, disorders of the adrenal axis, and acromegaly are included among the many causes of myopathy. Muscle disturbances caused by endocrine disorders are mainly due to alterations in the protein and carbohydrate metabolisms. Either a deficiency or excess of hormones produced by the glands can cause muscle dysfunction that can be reversed by starting hormone replacement therapy or acting on hormone dysfunction. The diagnosis is usually easy if a muscle disorder occurs in an overt endocrinopathy; however, in few patients, myopathy could be the first manifestation of the underlying endocrinopathy. In this article we discuss pathophysiology, clinical features and management of muscle involvement related to the major endocrine diseases.

Keywords: creatine kinase; endocrine myopathies; hypothyroidism; muscle weakness; myalgia; rhabdomyolysis.

Figure 1.

Histopathological findings in hypothyroid and hypercortisolism associated myopathies A: cores in type 1 fibers, NADH-TR (magnification 280 X); B: immunocytochemistry revealing increased desmin binding in two cores (magnification 280 X); C: Electron microscopy showing two core areas with disorganized myofibrils, rod bodies, and lack of mitochondria and glycogen (magnification 6800X); D: ATPase pH 9.4 stain showing a marked type 2 fibers atrophy in steroid myopathy (magnification 110 X).