This test is done to measure reverse T3, an inactive form of thyroid hormone produced when the body converts T4 in a different metabolic pathway. It helps evaluate how thyroid hormones are being processed in the body. Abnormal levels may be seen in illness, stress, fasting states, or complex thyroid function disturbances.

• If thyroid symptoms persist despite normal standard thyroid tests.
• If there is suspected altered thyroid hormone metabolism.
• If chronic illness or stress-related thyroid changes are being evaluated.
• If a healthcare provider is investigating complex thyroid disorders.