Rheumatic manifestations of autoimmune thyroid disease: the other autoimmune disease.

Autoimmune thyroid disease (AITD) is an inflammatory thyroiditis that in some cases is characterized by lymphocytic infiltration of the thyroid gland, also referred to as chronic lymphocytic thyroiditis or Hashimoto thyroiditis. Hashimoto thyroiditis is one of the commonest causes of hypothyroidism. Hypothyroidism has been associated with osteoarthritis (OA) and inflammatory forms of arthritis and with several well defined connective tissue diseases, which in turn can cause arthritis. The presence of arthritis in patients with AITD with normal thyroid function is now being increasingly recognized. There is also considerable evidence to suggest that AITD is highly associated with fibromyalgia syndrome. We review the current literature on the rheumatologic manifestations of AITD and describe the features in its presentation that set it apart from other forms of autoimmune arthritis.