Thyroiditis in myasthenia gravis

Three out of 40 patients with myasthenia gravis had chronic thyroiditis. The thyroid disease preceded the neuromuscular disorder in two patients, while the third developed a slowly progessive hypothyreosis during the course of the myasthenia. One patient had an initial thyrotoxicosis with subsequent development of hypothyreosis. Of the remaining 37 patients, two had enlarged thyroid glands, positive family history of thyroid disease and antibodies to thyroid globulin, but were euthyreot.