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Reverse Triiodothyronine (rT3)

Reverse T3 (rT3) is a thyroid hormone that is produced by the body from the conversion of the more active form of thyroid hormone, triiodothyronine (T3). While T3 plays an important role in regulating the body's metabolism, rT3 is thought to be a biologically inactive form of the hormone that serves as a marker of thyroid function. The production of rT3 is increased in situations of stress, illness, or starvation, and may serve as a protective mechanism to reduce the body's metabolic rate and conserve energy. However, in some cases, an increase in rT3 levels may be associated with thyroid dysfunction or other underlying medical conditions. A blood test can be performed to measure rT3 levels in the body. However, the interpretation of rT3 levels can be complex and should be done in conjunction with other thyroid function tests, such as measurements of thyroid-stimulating hormone (TSH), free T3, and free T4.

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