T3, Total (Triiodothyronine)
What it measures
T3 is one of the two main hormones your thyroid gland makes. Total T3 measures all of it in your blood, both the part attached to proteins and the free part.
When it’s ordered
Usually after a TSH result is off, or when thyroid symptoms continue. It is checked less often than TSH.
Medicare coverage
Medicare judges coverage case by case under its medical-necessity rules. The national thyroid testing rule (NCD 190.22) does not list this test, so the local Medicare contractor in your state may have its own rules.
Typical price
Medicare pays a set rate of $14.18 for this test (2026 fee schedule). When Medicare covers this test, you pay nothing. A lab can bill far more if you pay on your own or if Medicare denies the claim, so ask for the price first.
One thing to watch
Ask whether your doctor wants TSH alone or TSH plus T3. Each test is billed separately.
Look up the current Medicare allowable for T3, Total (Triiodothyronine) →
Rates and coverage rules shown apply to Original Medicare (Fee-for-Service) only. Medicare Advantage plans may differ. See our data sources →