Table 1.

Differential Diagnosis of Thyrotoxicosis and Tests That May Help Distinguish among the Various Causes.

Cause	Thyroid Iodine-123 Uptake	Thyroid Peroxidase Antibodies	Thyroid-Stimulating Immunoglobulin	Thyroglobulin
Graves’ disease	Elevated	Usually positive	Usually positive	Increased
Toxic nodular goiter	Elevated	Negative	Negative	Increased
Thyrotropin-secreting pituitary adenoma	Elevated	Negative	Negative	Increased
Trophoblastic tumor	Elevated	Negative	Negative	Increased
Hyperemesis gravidarum	Elevated	Negative	Negative	Increased
Painful thyroiditis	Low	Negative	Negative	Increased
Silent lymphocytic thyroiditis	Low	Usually positive	Negative	Increased
Drugs (amiodarone, interferon alfa, and lithium)	Low	Usually negative	Negative	Increased
Iodine-induced hyperthyroidism	Low	Usually negative	Negative	Increased
Struma ovarii	Low	Negative	Negative	Increased
Thyrotoxicosis factitia	Low	Negative	Negative	Decreased