Reverse T3

The Reverse T3 (rT3) test measures the level of reverse T3 in the blood. Reverse T3 is an inactive form of the thyroid hormone thyroxine (T4) and is produced when T4 is metabolized. This test is used to assess thyroid function, particularly in cases where there are symptoms of thyroid dysfunction but normal TSH and T4 levels, and to evaluate conditions affecting thyroid hormone metabolism.

Sample type:

Serum

Preparation:

You do not need to do anything special to prepare for the sample collection. Fasting is not required for this test.

Test type:

In person or via trained mobile phlebotomist

Biomarkers

T3, Reverse

Symptoms or conditions analyzed by this test

The Reverse T3 test evaluates thyroid hormone metabolism and helps diagnose conditions where traditional thyroid function tests may be misleading. Elevated rT3 levels can be associated with symptoms like fatigue, weight gain, and general hypothyroid symptoms, often seen in non-thyroidal illness syndrome or under conditions of chronic stress or malnutrition. The test is useful for assessing thyroid function in complex scenarios where TSH and T4 levels alone do not fully explain the patient’s symptoms.

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