EVALUATION OF THYROTOXICOSIS

Measure TSH, unbound T₄

TSH low, unbound T₄ high

TSH low, unbound T₄ normal

TSH normal or increased, high unbound T₄

TSH and unbound T₄ normal

TSH-secreting pituitary adenoma or thyroid hormone resistance syndrome

No further tests

Subclinical hyperthyroidism

Follow up in 6-12 weeks

Graves' disease

Toxic nodular hyperthyroidism

Destructive thyroiditis, iodine excess or excess thyroid hormone

Rule out other causes including stimulation by chorionic gonadotropin

^a  Diffuse goiter, positive TPO antibodies, ophthalmopathy, dermopathy.

^b  can be confirmed by radionuclide scan.

End

Measure unbound T₃

High

Normal

Yes

No

Low radioiodine uptake?

Yes

No

T₃ toxicosis

TSH, thyroidstimulating hormone.

Primary thyrotoxicosis

Features of Graves' disease^a  ?

T₃ toxicosis

Multinodular goiter or toxic adenoma^b  ?

Yes

No