Similar to T3 Free, the T3 Total test is a blood test that measures the total amount of T3 hormone in your bloodstream, both bound and unbound.
There are a few reasons why your doctor might order a T3 Total test:
Thyroid disease: As with the T3 Free test, abnormal T3 Total levels can indicate thyroid disease. An overactive thyroid (hyperthyroidism) can cause high T3 Total levels, while an underactive thyroid (hypothyroidism) can cause low T3 Total levels.
Monitoring thyroid treatment: If you are receiving treatment for thyroid disease, such as medication to regulate thyroid hormone levels, your doctor may order a T3 Total test to monitor your response to treatment.
Suspected protein binding issues: The T3 hormone is mainly bound to proteins in the blood, such as thyroxine-binding globulin (TBG), transthyretin, and albumin. In rare cases, certain medical conditions or medications can affect protein levels and cause changes in T3 Total levels.
It’s important to note that the T3 Total test is not always a reliable indicator of thyroid function, as it measures both bound and unbound T3, and protein levels in the blood can vary. For this reason, the T3 Free test is often considered more accurate for assessing thyroid function. Your doctor will consider your specific medical history and symptoms when deciding which tests to order.