Endocrine Myopathies

Abstract

Myopathies are associated with a number of different endocrine disorders (Table 18.1). In these “endocrine myopathies” the onset of weakness is insidious, proximal muscles are predominantly affected and recovery generally occurs when the endocrine disorder is corrected. In addition to myopathies occurring with endocrine disease, myopathic weakness may also occur when certain hormones are used in treatment. For example, longterm steroid therapy often leads to a steroid-dependent proximal myopathy. In most instances the myopathy associated with endocrine disease is a minor part of the clinical disorder but sometimes, as in some patients with thyrotoxic myopathy, muscular symptoms may be a presenting feature of the endocrine disorder. Occasionally endocrine myopathies may show more complex clinical features as in thyrotoxic myopathy in which myasthenic weakness may sometimes occur.