Free T3, Free T4, RT3 and TSH Panel Most Popular

The Free T3, Free T4, RT3 and TSH Panel panel contains 4 tests with 5 biomarkers.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Free T3, FT3, T3 Free

T3, Free

This test measures the amount of triiodothyronine, or T3, in the blood.

Also known as: Free T4, FT4, T4 Free

T4, Free

The free T4 test is not affected by protein levels. Since free T4 is the active form of thyroxine, the free T4 test is may be a more accurate reflection of thyroid hormone function.

Also known as: Thyroid Stimulating Hormone, Thyroid Stimulating Hormone (TSH), Thyrotropin

TSH

A TSH test is a lab test that measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland. It tells the thyroid gland to make and release thyroid hormones into the blood.

TSH

Also known as: Reverse T3, Reverse Triiodothyronine, RT3, T3 Reverse RT3 LCMSMS, Triiodothyronine Reverse

T3 Reverse, LC/MS/MS

Reverse T3 produced in the thyroid comes from the conversion of the storage hormone T4. Your body, especially the liver, can constantly be converting T4 to RT3 as a way to get rid of any unneeded T4. In any given day approx. 40% of T4 goes to T3 and 20% of T4 goes to Reverse T3. Hoever in any situation where your body needs to conserve energy and focus on something else, it will change the above percentages, changing the conversion of RT3 to 50% or more, and the T3 goes down, down. Examples are emotional, physical, or biological stress, such as being chronically or acutely sick (the flu, pneumonia, etc), after surgery, after a car accident or any acute injury, chronic stress causing high cortisol, being exposed to an extremely cold environment, diabetes, aging, or even being on drugs like beta blockers and amiodarone.