TestWell Price
$22.99
+ $6 lab processing fee
Thyroxine (T4) is the main hormone the thyroid produces, and it circulates in two forms: bound to carrier proteins and free. Total T4 measures the whole pool and reflects overall thyroid output; Free T4 measures only the unbound, biologically active fraction that tissues can actually use. Ordering both together separates a true change in thyroid output from a change in binding proteins — which shift with estrogen, pregnancy, oral contraceptives, liver disease and some medications — and gives a fuller picture than either value alone. Typically ordered alongside TSH when thyroid function is being established or monitored.
Sample Type
Blood draw
Fasting
Not required
Results In
1–3 business days
Performed At
Quest or Labcorp
Your T4, Free & Total (Thyroxine) results will include values for each of the 2 biomarkers tested, along with reference ranges. Results are reviewed by a licensed physician before being released to your secure portal.
If any values fall outside the normal range, your report will include guidance on what that may mean and recommended next steps. You'll receive an email notification when your results are ready, typically within 1–3 business days.
Typical reference range layout
Lab reports show where your value sits relative to established reference intervals—your physician interprets this in context for you.
Your T4, Free & Total (Thyroxine) results will include values for each of the 2 biomarkers tested, along with reference ranges. Results are reviewed by a licensed physician before being released to your secure portal.
If any values fall outside the normal range, your report will include guidance on what that may mean and recommended next steps. You'll receive an email notification when your results are ready, typically within 1–3 business days.
Typical reference range layout
Lab reports show where your value sits relative to established reference intervals—your physician interprets this in context for you.
No fasting required. Biotin supplements can interfere with thyroid assays — skip them for 48 hours before your draw if possible.
No fasting required. Biotin supplements can interfere with thyroid assays — skip them for 48 hours before your draw if possible.
TestWell Price
$22.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Frequently ordered together
Customers who ordered T4, Free & Total (Thyroxine) also added these for a more complete health picture.
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T4, Free & Total (Thyroxine)
$22.99