Thyroid Profile (T3, T4, TSH)
Blood tests that check how well your thyroid gland is working by measuring thyroid hormones and the hormone that controls them.
Thyroid Profile (T3, T4, TSH)
Blood tests that check how well your thyroid gland is working by measuring thyroid hormones and the hormone that controls them.
Also known as
- T3 T4 TSH
- Thyroid function tests
What it measures
- TSH (thyroid-stimulating hormone), made by the pituitary gland, which tells the thyroid how much T3 and T4 to make
- T3 (triiodothyronine)
- T4 (thyroxine)
Why a doctor may order it
A doctor may ask for it if you have symptoms that could come from too much or too little thyroid hormone. People who take thyroid hormone medicine have regular TSH tests to check the dose.
What it helps evaluate
It can show whether the thyroid is making too much (hyperthyroidism) or too little (hypothyroidism) hormone. A TSH test alone can't show what is causing a thyroid problem.
Preparation
You generally don't need special preparation for a T3 or T4 test. Some medicines and supplements can affect results, so tell your provider about everything you take — and don't stop any medicine unless your provider tells you to.
Fasting
If other blood tests are ordered on the same sample, you may need to fast. Your provider or the lab will tell you.
Important considerations
- T3 results are usually read together with TSH and T4 results.
Discuss results with your doctor
Talk to a doctor about your symptoms and about what your results mean — a single result is not a diagnosis. See a doctor promptly for severe or worsening symptoms.