Thyroid, T4, FT4, T3 Uptake, TSH

The Thyroid, T4, FT4, T3 Uptake, TSH panel contains 4 tests with 6 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.

T3 Uptake

T3 uptake is also known as T3 Resin Uptake (T3RU) or Thyroid Uptake. It estimates how much thyroid hormone-binding proteins are available in the blood through a calculation based on levels of T3 or T4 added to a person's blood specimen.

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: T4 Thyroxine Total

T4 (Thyroxine), Total

This test measures the amount of thyroxine, or T4, in the blood. T4 is one of two major hormones produced by the thyroid gland. The total T4 test is used to help diagnose hyperthyroidism and hypothyroidism. It is a useful test but can be affected by the amount of protein available in the blood to bind to the hormone.

Free T4 Index (T7)

FTI stands for the Free Thyroxine Index and is also sometimes referred to as T7. It is a calculated value determined from the T3 uptake test and total T4 test and provides an estimate of the level of free T4 in the blood.

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