Approach to Thyroid Function Tests in the Evaluation of Hyperthyroidism

 • Low TSH, Low normal T4 → Possibly Central Hypothyroidism. unlikely subclinical hyperthyroidism.

 • Low TSH, normal T4 +/- T3 → Subclinical Hyperthyroidism: Work-up similar to hyperthyroidism as below. Can repeat labs 6 weeks after the resolution of pregnancy, critical illness, and dopamine agonists/octreotide.

 • Low TSH, high T4 +/- T3 → Primary Hyperthyroidism

    → Signs of symmetrically enlarged thyroid & ophthalmopathy → Graves' Disease → Confirm with TRAb

    → Radioactive Iodine Uptake & Scan

 • High or normal TSH, high T4 +/- T3 → Central (secondary) Hyperthyroidism → MRI Pituitary



- Dr. Claire Brickson @crbricks



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