Total T4 Test
Total T4 Test is a laboratory test you can order directly. A total T4 test measures the total amount of thyroxine (T4), a thyroid hormone, in your blood. It is often ordered to help evaluate thyroid function when symptoms such as fatigue, weight changes, or irregular heartbeat are present.
- Sample type
- blood
- Category
- Thyroid
- Turnaround
- 1-3 business days
- Price
- $49
- Referral
- Not required
A total T4 test measures the total amount of thyroxine (T4), a thyroid hormone, in your blood. It is often ordered to help evaluate thyroid function when symptoms such as fatigue, weight changes, or irregular heartbeat are present.
What it measures
- Total T4 — The combined amount of T4 that is free and bound to proteins in the blood.
- Free T4 (indirect) — Sometimes calculated from total T4 and a protein measurement, but not directly measured in this test.
- Thyroxine-binding globulin (TBG) — A protein that binds T4; not directly measured, but its levels can affect total T4 results.
Who it is for
A healthcare provider typically orders a total T4 test when checking for an overactive or underactive thyroid, or to monitor thyroid treatment.
Preparation
No fasting is required. Tell your provider about any medications, especially thyroid drugs or birth control, as they can affect results.
Results and what they mean
Results are reported as a number with a reference range, usually in micrograms per deciliter (mcg/dL). A clinician interprets your result along with your symptoms, history, and other thyroid tests. This is general information, not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the total t4 test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to fast for a total T4 test?
No, fasting is not needed. You can eat and drink normally before the blood draw.
What can affect my total T4 result?
Pregnancy, birth control pills, and some medications can raise or lower total T4. Always share your medication list with your provider.
Is total T4 the same as free T4?
No. Total T4 includes both bound and free hormone, while free T4 measures only the unbound, active portion. They are different tests.
How long until I get my results?
Results are typically available within 1 to 3 business days.