Individual test · Labcorp 001156

T3 Uptake

This test measures the available space on proteins in your blood that carry thyroid hormones. It is usually paired with a T4 test to calculate how much thyroid hormone is free for your body to use, which helps evaluate if your thyroid is overactive or underactive. This comparison helps rule out whether abnormal test results are caused by actual thyroid disease or by other factors like pregnancy or medication that affect blood proteins. The T3 Uptake test does not measure the actual level of T3 hormone in your blood and cannot provide a diagnosis when used alone.