T4 (Thyroxine), Total Only - T4

otal T4 measures both bound and free forms of the thyroid hormone thyroxine in the blood, providing an overall indication of thyroid hormone production.

While useful for assessing thyroid function, interpretation is affected by changes in binding proteins (such as TBG) and non-thyroidal illnesses; many providers prefer Free T4 for a clearer picture of active hormone.