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* This is not a home test kit. You will need to visit a local lab for testing.
Fasting Required: No
Turnaround Time: 2-10 business days
Specimen Type: Blood
Direct Free T4, Free T4 by Equilibrium Dialysis, Free Thyroxine, FT4 Direct Dialysis
A free thyroxine blood test help assesses thyroid health and detects thyroid problems and other related health conditions.
The T4 free blood test measures free thyroxine (T4) in the blood to assess thyroid health. Thyroxine is a hormone produced by the thyroid gland and secreted in the bloodstream.
T4 can be classified into two forms: free thyroxine (FT4) and bound T4. Of the two, FT4 is considered the most accurate in detecting thyroid disease, as it evaluates T4 that enters any tissue that needs it. Whereas, bound T4 is attached to some proteins.
Take a free T4 blood test as a complementary test for TSH and T3 bloodwork. Additionally, consider the free T4 test, if you have hypothyroidism or hyperthyroidism symptoms, which include the following.
Hypothyroidism Symptoms
Hyperthyroidism Symptoms
No special preparation is needed prior to blood sample collection.
The normal range for free T4 is 0.9 to 2.2 nanograms per deciliter (ng/dL).
Test values that go beyond or below the reference interval may suggest thyroid problems. However, the result cannot be conclusive unless other tests are performed, such as the TSH (thyroid-stimulating hormone) blood test, T3, total blood test, T4 Total blood test, and other thyroid blood tests.
High T4 can be linked to medical conditions like Grave’s disease, thyroiditis (thyroid inflammation), thyroid nodules, and goiter. It can also be attributed to too much intake of thyroid medicine, hormonal changes (especially among women), and liver problems.
On the other hand, low T4 can indicate hypothyroidism, thyroiditis, and malnutrition. Again, these illnesses require additional tests for accurate diagnosis. Simplify the process by taking note of the symptoms you observe.
Taking a free thyroxine test can be carried out with these four steps.
Step 1: Go to our website’s thyroid function tests section, and order the thyroxine (T4) free, direct blood test. Then print out the lab test order, which doubles as your doctor’s order for the lab work.
Step 2: Using our lab locator, select a patient partner center where you can have the test done.
Step 3: Proceed to the laboratory you chose during your scheduled blood collection.
Step 4: Wait for the lab test results within 2-10 business days in your Personalabs account.
For an exact turnaround time for results, please contact us at 1-888-438-5227. We will contact the lab of your choice (Quest Diagnostics or LabCorp) as turnaround times vary depending on testing location or lab testing provider.
Provider | LabCorp, Quest |
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Results can be provided in as little as 24-48 hrs. For more complex tests, please contact us for turn around times.