$25.00
Priced per marker, with baseline labs included. You’ll see your total before you pay.
Thyroid
Reverse T3 test
Inactive form of T3; can rise with stress, illness, or extreme calorie restriction.
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
Reverse T3 is an inactive form of thyroid hormone. Your body can make more of it during illness, physical stress or strict dieting, as a way to save energy.
Why it matters for women
Thyroid conditions are much more common in women, and some women ask about reverse T3 when they feel tired but their standard thyroid results look normal. Most doctors rely on TSH and free T4, the standard thyroid tests, since reverse T3 on its own rarely changes the picture. Strict dieting or intense training can raise it.
You might check it if…
- you’ve been through a major illness, heavy stress or strict dieting
- a doctor wants more detail beyond your standard thyroid tests
What your result may mean
High Reverse T3: what it may mean
High reverse T3 may suggest your body is converting less T4 into active T3 and making more of this inactive form. It can happen with stress, severe illness, fasting, chronic disease, strict dieting or intense training. Some medicines, such as amiodarone or steroids, can raise it too. You may feel tired, but that can come from many things, and reverse T3 on its own can rarely change the picture. Many clinicians may rely on TSH and free T4 first.
Low Reverse T3: what it may mean
Low reverse T3 may not be a concern on its own, and it may go along with efficient thyroid hormone conversion. It can also occur with an underactive thyroid (hypothyroidism), when less T4 is around to convert. Because of that, a low value can’t tell you your thyroid is healthy. Tiredness or feeling cold can be worth raising if you notice them, since TSH and free T4 can give a clearer answer. Many people with a low reverse T3 may have no symptoms from it.
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These notes provide context and do not diagnose a condition. Not yet available in NY, NJ, RI, HI, ND, SD or WV.