T3 Uptake

Overview:

T3 uptake does not measure thyroid hormone. It measures how many binding sites on thyroid hormone transport proteins are still available, which indirectly indicates whether those protein levels are unusual. Its purpose is to correct a total T4 result, since a total can be misleading when binding proteins are raised or lowered, as happens in pregnancy, with estrogen use and in some illnesses. Combining T3 uptake with total T4 produces the Free T4 Index. Direct free T4 measurement has largely replaced this approach, so the test is now mainly seen as part of older panel combinations.

Categories:

Thyroid

Biomarkers:

1 biomarker