The differential diagnosis for an elevated serum TSH level includes primary hypothyroidism; the hypothyroid phase of subacute thyroiditis; recovery from nonthyroidal illness; drugs, including dopamine antagonists, amiodarone, and oral cholecystogram dye (sodium ipodate); TSH-producing pituitary adenoma; adrenal insufficiency; and generalized thyroid hormone resistance. Ingestion of excess exogenous thyroid hormone would suppress the TSH level.
