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Free T4 Blood Test

Free T4, T4 Free, Free Thyroxine, Thyroxine (T4), Free, Direct
Sample Report
Specimen Type: Blood


Free T4 Blood Test

This test measures the amount of unbound or free Thyroxine (T4) in a person's system.  T4 is a hormone produced by the thyroid gland which helps maintain the body's metabolism, temperature, and heart rate.  Most T4 in the body is bound to proteins.  A free T4 test measures the level of T4 which is not bound to any proteins.  In some cases, such as when a person's protein levels are irregular or fluctuating,  a free T4 measurement can provide a more accurate assessment of thyroid function than a regular T4 test.  Measuring Free T4 can aid in the diagnosis of a number of conditions which affect the thyroid.

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 T4 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.  A TSH and Free T4 test is available for those who wish to run both of these tests together. 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 T4 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 T4 test has no fasting requirements. Collection should not occur during or after administration of heparin.



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Offer expires December 14, 2016.


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