• Free T4
1 1

Free T4

Free T4

$35.00
$50.00 $35.00
Sale Sold out

The Free T4 test measures the level of free thyroxine (T4) in your blood, which is an essential hormone produced by the thyroid gland. This hormone helps regulate various bodily functions, including metabolism, energy production, and overall hormonal balance. Unlike total T4, the Free T4 test assesses the unbound form of the hormone, giving a clearer picture of your thyroid function. Abnormal Free T4 levels can indicate conditions such as hypothyroidism or hyperthyroidism, leading to symptoms like fatigue, weight gain, or anxiety. This straightforward test is a crucial step in evaluating thyroid health.

View full details

About This Test

Reason to Check It

"The thyroid actually produces both free T4 and free T3, and the majority it produces in response to signaling from the brain is free T4.  Each cell in our body is responsible for converting the inactive free T4 into the active free T3 and it is thought that approximately 15% of the population do not convert well and have lower than expected free T3 levels." - Dr. Alan Hopkins

Test Preparation

  • No special preparation is required before your sample collection.


Please Note: We recommend overnight fasting and an early morning blood draw for all tests, even if no special preparation is required. Remember, it is OK to drink plenty of water. Drinking water helps hydrate you and makes it easier for the phlebotomist to obtain your blood sample.

Test Type and Method

Test Type:

  • Blood


Test Method:

  • In-person Blood Draw

Post-Test Notes

  • Once your specimen is collected, test results are typically processed and available within a few business days. Processing times may vary depending on the test. Your results will be delivered in a clear, easy-to-understand report. If any values fall outside the expected range, you may receive a follow-up call from an independent healthcare coordinator.

Lab Testing is Simple, Fast, and Convenient

Choose the Individual Test or Lab Panel that suits your health needs. You’ll receive your lab requisition within 24 hours. Visit any of the 3,000+ Quest Diagnostics centers using the button below. Once your sample is collected, your results will be securely delivered via email within 7–10 days.

View Quest Draw Locations

Lab Testing is Simple, Fast, and Convenient

Choose the Individual Test or Lab Panel that suits your health needs. You’ll receive your lab requisition within 24 hours. Visit any of the 3,000+ Quest Diagnostics centers using the button below. Once your sample is collected, your results will be securely delivered via email within 7–10 days.

View Quest Draw Locations