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Free T3 Blood Test

Free T3, Triiodothyronine (T3), Free
Sample Report
Specimen Type: Blood


Free T3 Blood Test

This test measures the amount of unbound or free Triiodothyronine (T3) in a person's system.  T3 is a hormone which helps control the body's metabolism, temperature, and heart rate.  Production of T3 is linked to the production of Thyroid Stimulating Hormone (TSH) by the pituitary gland.  T4, another hormone produced by the thyroid gland, is often converted into T3 in the liver and other body tissues.  Most T3 in the body is bound to proteins.  A Free T3 test measures the level of T3 which is not bound to any proteins.  In some cases such as when a person's protein levels are irregular or fluctuating, a free T3 measurement can provide a more accurate assessment of thyroid function that a regular T3 test.  Irregular T3 levels may be caused by thyroid disorders such as hyperthyroidism or hypothyroidism.

Common symptoms of thyroid disorders include but are not limited to anxiety, irregular weight gain or loss, insomnia, diarrhea, constipation, irritation or sensitivity in the eyes, increased heart rate, dry skin, hair loss, and menstrual irregularity in women.

Free T3 is a common test ordered to help evaluate a person's thyroid function, especially if they have had irregular results from other thyroid tests or are experiencing symptoms which are associated with thyroid disorders such as hyperthyroidism or hypothyroidism.  Customers looking for a more in depth thyroid testing package may wish to order our Thyroid Comprehensive Panel with Free.

Turnaround time for a Free T3 test is typically 1 business day.

Note: Result turn around times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.


This Free T3 test has no fasting requirements.



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for the month of 



Take 14% off all testing.

Use coupon code ANNIV14 during checkout.

Offer expires December 14, 2016.


Cannot be applied to industry discounted prices, previous orders or tests not listed on our website. One coupon code per order. Coupon code expires at Midnight EST.