Multiple sclerosis and Hashimoto thyroiditis: two cases.

Multiple sclerosis (MS) occurs with immune-mediated mechanisms, but its pathogenesis is not accurately known. The coexistence of MS with other autoimmune diseases has been reported. The hypothesis that MS coexists with other autoimmune diseases has been supported by the reported association of MS with type I diabetes mellitus and inflammatory disorders. Even though there have been only rare reports of associations between Hashimoto thyroiditis and MS, this association is important for its clinical and therapeutic aspects. Proximal muscle weakness, myalgia, and fatigue are symptoms that are common in both MS and hypothyroidism. When MS patients demonstrate these symptoms, thyroid function tests should be performed. The thyroid hormone levels of MS patients being treated with interferon-beta and Campath-1H also should be monitored. The authors report the clinical data of 2 definite MS patients who also fulfilled criteria for Hashimoto thyroiditis.