The T-Uptake test measures the availability of thyroid hormone–binding sites in the blood, indirectly reflecting levels of thyroid-binding proteins, particularly thyroid-binding globulin (TBG). It does not measure thyroid hormone levels directly, but helps interpret total T4 results.
This test is commonly used in combination with Total T4 to calculate the Free Thyroxine Index (FTI), which provides an estimate of active thyroid hormone levels. T-Uptake is helpful when conditions such as pregnancy, estrogen therapy, liver disease, or medication use may alter thyroid-binding proteins and affect total thyroid hormone measurements.
T-Uptake
The T-Uptake test measures the availability of thyroid hormone–binding sites in the blood, indirectly reflecting levels of thyroid-binding proteins, particularly thyroid-binding globulin (TBG). It does not measure thyroid hormone levels directly, but helps interpret total T4 results.
This test is commonly used in combination with Total T4 to calculate the Free Thyroxine Index (FTI), which provides an estimate of active thyroid hormone levels. T-Uptake is helpful when conditions such as pregnancy, estrogen therapy, liver disease, or medication use may alter thyroid-binding proteins and affect total thyroid hormone measurements.
