Total T3
All the T3 thyroid hormone in your blood, from one blood draw.
- 2,000+ lab locations. Find one near you
- Nothing due at the lab. FSA / HSA accepted
- Ordered by a licensed clinician
At a glance
- Collection
- Blood drawA standard blood draw at the lab.
- Preparation
- NoneNothing to do ahead of time. Water is fine.
- Results
- 1 to 3 daysTypical turnaround after your visit.
- Where
- 2,000+ lab locationsNationwide, with nothing due at the lab.
About this test
Total T3 measures all the T3 in your blood, both the part attached to carrier proteins and the unbound part. T3 is a thyroid hormone, and much of it is made from T4 in the body’s tissues. It is mainly used for overactive thyroid questions, usually after TSH. No fasting is needed.
For adults 18 and older. Test availability varies by lab location.
Who should take this test?
Usually checked after a low TSH or when symptoms suggest an overactive thyroid, total T3 is read with TSH and other thyroid results. Commonly related symptoms include:
Heart
- Racing heartbeat
Body
- Feeling hot or sweaty
- Shaky hands
Weight
- Unexplained weight loss
Mood
- Feeling anxious or on edge
Family history
- Thyroid conditions in family
Ask about this test
Not sure this is the right test?
AI-generated. For information only, not medical advice. Call 911 for an emergency.
What does this test measure?
Your result shows how much T3 is in your blood in total, which can help a healthcare provider look into an overactive thyroid question alongside TSH and Free T4.
- Total T3
- Total T3 measures both the bound and unbound forms of triiodothyronine in your blood. Because most T3 is bound to proteins, the result can shift with changes in those proteins, for example with pregnancy or some medicines. It is mainly used when an overactive thyroid is a question.
- Why it’s measured: Bound plus unbound T3, mainly used when an overactive thyroid is a question.
How it works
- Step 1
Order online
Check out here. A licensed clinician in your state reviews your order and sends it to the lab.
- Step 2
Visit a lab
Bring a photo ID to any of 2,000+ lab locations. No fasting needed, and nothing is due at the lab.
- Step 3
Get your results
Results post to your account, usually in 1 to 3 days, each number next to the lab’s reference range.
Find a lab near you
Choose from 2,000+ lab locations nationwide. Your order works at any of them.
What your results tell you
Total T3 is reported in nanograms per deciliter (ng/dL) and shown next to the lab’s reference range for comparison.
- Your number next to the lab’s reference range
- Explained in plain language
- A licensed clinician reviews your order and, if appropriate, orders the test.
- A lab report you can download and share
A total T3 outside the range is read with TSH and Free T4. A healthcare provider can explain your result and any next steps.
Total T3 or Free T3?
Two ways to measure the same hormone.
Total T3
All the T3 in your blood, bound and unbound.
- Measures
- Bound and unbound T3 together
- Carrier proteins
- Can shift when their levels change
- Mainly used for
- Overactive thyroid questions, read with TSH
Clinical-grade testing, from the comfort of home.
From the lab to your report, every step of our process meets the gold standard in medical testing.
CLIA-certified labs
Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.
We protect your health data
We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.
Rigorous quality assurance
All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.
Clinician-reviewed reports
Results are reviewed by an independent, licensed clinician.
Related tests
Questions
Common questions.
Anything else, our care team answers by phone, text, or email.
Total T3 is used in evaluating and following an overactive thyroid. In one form of overactive thyroid, T3 rises more than T4, which is one reason T3 is checked when TSH is low but Free T4 is within range.
Most T3 in the blood is carried by proteins. If the amount of those proteins changes, total T3 can shift even when thyroid activity hasn’t. Free T3 measures the unbound portion and is less affected. A healthcare provider can explain which fits your question.
Not usually. In an underactive thyroid, T3 may not drop until well after TSH and Free T4 have changed, so TSH and Free T4 are the usual checks for that question. A healthcare provider reads total T3 together with those results.
No. This test is not for emergencies. If you have chest pain, a racing or irregular heartbeat that does not settle, fainting, trouble breathing, or sudden confusion, get emergency care right away rather than waiting for a lab visit or a result.
Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.