T3 Uptake LabCorp

T3 Uptake is an indirect measurement of the available binding sites for the thyroid stimulatory hormones from the brain. T3 uptake is not a measurement of T3 and should never be used alone. This is best used in conjunction with T4 and Free T3. T3 uptake can be abnormal with thyroid dysfunction, malnutrition, and kidney disease. Additionally, abnormal T3 uptake can be seen with the use of oral contraceptives and hormone prescription, such as testosterone and estrogen. Fasting is not required for this test and it is recommended to take all medications as prescribed.