Compare markers
TSH vs free T4
TSH and free T4 are complementary thyroid markers that laboratories often report together.
General biomarker education — not personalized medical advice. Learn more
TSH
TSH is a pituitary hormone measured when clinicians evaluate thyroid-related lab context.
Free T4
Free T4 measures the unbound, active portion of thyroxine, a thyroid hormone.
Why both appear on reports
Thyroid screening frequently pairs TSH with a free T4 measurement to provide context for each result.
When to discuss with your clinician
Ask how these values compare with prior thyroid labs and whether repeat testing is planned.