T3 Total

Overview:

T3 is the more active of the two main thyroid hormones. Most of it is produced by converting T4 in tissues rather than by the thyroid directly. A total T3 measures both the protein-bound and unbound portions together, so results are affected by conditions that change binding protein levels, including pregnancy and estrogen use. Its most useful role is in assessing an overactive thyroid, where T3 can be raised while T4 is still normal. It is less useful for underactive thyroid, since T3 is often maintained until the condition is well advanced.

Categories:

Thyroid

Biomarkers:

1 biomarker