Thyroxine (T4) Free, Direct

The Free Thyroxine (T4), Direct test measures the level of free thyroxine (T4) in the blood. Free T4 represents the fraction of T4 hormone that is not bound to proteins and is available to enter cells and exert its effects. This test is used to assess thyroid function and diagnose conditions related to thyroid hormone imbalances, such as hypothyroidism and hyperthyroidism.

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

T4 Free, Thyroxine

Symptoms or conditions analyzed by this test

The Free Thyroxine (T4), Direct test measures the level of unbound T4 hormone in the blood to assess thyroid function. High levels of free T4 are indicative of hyperthyroidism, with symptoms including weight loss, rapid heart rate, and heat intolerance. Low levels of free T4 suggest hypothyroidism, which may cause fatigue, weight gain, and sensitivity to cold. This test is essential for diagnosing thyroid conditions and evaluating the effectiveness of treatment.

Question 1