T3 Uptake Blood Test - More Information

The T3 uptake test, also known as a resin T3 uptake blood test or rT3U test, measures the T3 uptake blood level.

Although less commonly ordered these days, the T3 uptake test has been used to evaluate the effectiveness of proteins used to transport thyroid hormones. In particular, the T3 uptake blood test and the total T4 test can be multiplied to calculate the free thyroxine index (FTI or T7). FTI has historically been used to help evaluate the thyroid in the setting of thyroid binding protein issues.

To get a resin T3 uptake blood test near you, simply order online and get tested at an affiliated lab. Once your T3 uptake lab results are ready, they can be downloaded. As can be seen on the sample T3 lab report, T3 levels are reported as a number and can be compared against the rT3u ranges provided by the lab to help assess whether the T3 uptake levels are low or high.

An elevated T3 uptake level might be associated with hyperthyroidism which is why it is sometimes ordered with the hyperthyroidism test panel. Conversely, a low T3 uptake level is associated with hypothyroidism which is why it is sometimes ordered with the hypothyroidism test panel. The T3 test is a component of the comprehensive thyroid test panel.