$7.00
Priced per marker, with baseline labs included. You’ll see your total before you pay.
Thyroid
Total T3 test
Total triiodothyronine. Total triiodothyronine — active thyroid hormone in protein-bound and free forms.
At a glance
In about 5 days
Most results are ready in about 5 days. Some specialty markers can take up to 21 days.
Check before your draw
This marker has no preparation tag, but it can still need preparation. Contact us before your draw if you’re not sure.
Walk in at Quest
Your lab order arrives by email. Most Quest locations take walk-ins, so bring it with a photo ID.
What it measures
T3 is your body’s most active thyroid hormone. This test counts all of it in your blood, both the part carried by proteins and the small free part.
Why it matters for women
An overactive thyroid, which can come from Graves’ disease, an autoimmune condition, is much more common in women and can cause a racing heart, weight loss and shakiness. Pregnancy and estrogen, such as from birth control pills, can raise the proteins that carry thyroid hormone, which can push total T3 up even when your thyroid is fine.
You might check it if…
- your heart races or your hands shake for no clear reason
- you’ve lost weight without trying
- you often feel too hot or sweaty
- a doctor is checking for an overactive thyroid
What your result may mean
High Total T3: what it may mean
High total T3 may suggest an overactive thyroid (hyperthyroidism), such as Graves’ disease, as well as thyroiditis or too much thyroid hormone replacement. Pregnancy and estrogen, such as from birth control pills, can raise the proteins that carry thyroid hormone, which can push total T3 up even when your thyroid is fine. A racing heart, weight loss, shakiness or feeling hot may appear. Biotin can affect some thyroid tests, so a clinician may ask what supplements you take and look at TSH and free T4.
Low Total T3: what it may mean
Low total T3 may occur with an underactive thyroid (hypothyroidism), severe illness (euthyroid sick syndrome) or starvation. Androgens and steroid medicines can lower the proteins that carry T3, so the total can read low even when your thyroid is fine. Fasting and hard calorie cutting can bring it down too, and a low value during an illness may pass as you recover. You may notice tiredness, feeling cold, constipation or heavier periods. TSH can say more about an underactive thyroid than T3 can.
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No insurance required · HSA/FSA eligible · No subscription
These notes provide context and do not diagnose a condition. Not yet available in NY, NJ, RI, HI, ND, SD or WV.