Addisonian crisis precipitated by thyroxine therapy: a complication of type 2 autoimmune polyglandular syndrome.

Hypothyroidism is a common condition. Rarely, it may occur in combination with autoimmune failure of other endocrine glands (autoimmune polyendocrinopathy syndrome type 2, previously known as Schmidt's syndrome). In such cases, restoring normal thyroid function may precipitate adrenal failure. Clinicians should have a high index of suspicion for this condition in patients with Addison's disease, those with a family history of autoimmune endocrine gland failure, patients with one autoimmune endocrine disease who develop nonspecific or serious illness, and patients with type 1 diabetes mellitus whose insulin requirements drop without obvious explanation.