FREE TRIIODOTHYRONINE (FT3) Test
2,355 Kshs | Home Collection Available
Synonyms
FT3
Purpose of the FT3 Test
The Free Triiodothyronine (FT3) test measures the level of free T3 hormone, an active thyroid hormone, in the blood. This test helps assess how well the thyroid gland is functioning and plays a key role in diagnosing and monitoring thyroid disorders.
FT3 is important because it influences several body functions, including metabolism, heart rate, and body temperature. Abnormal levels may indicate conditions such as hyperthyroidism, hypothyroidism, or thyroid hormone resistance.
Other tests commonly performed alongside this test include TSH (Thyroid Stimulating Hormone) test, Free T4 (Thyroxine) test, thyroid antibody tests, thyroid ultrasound or scan
Together, these tests provide a comprehensive picture of thyroid health and guide accurate diagnosis and treatment.
Patient Preparation
The patient should avoid taking biotin supplements at least 72 to sample collection.
Samples
1ml with a minimum volume of 0.7ml of serum or plasma collected Gel-barrier, red-top, or green-top tube (lithium heparin). Avoid using EDTA, oxalate, or citrate plasma. Transfer separated serum to a plastic transport tube if a red top tube is used. Store the sample at room temperature.
FT3 Test Reference Range
>19 years;2.0-4.4pg/mL
Results Turnaround
1-2 days after receipt of samples.
Diseases / Diagnostic indicators
The FT3 test helps confirm thyroid-related conditions, especially hyperthyroidism and T3 toxicosis, a form of hyperthyroidism where only T3 is elevated while T4 and TSH may appear normal.
Possible outcomes of the FT3 test include:
- Elevated FT3 levels may indicate:
- Hyperthyroidism (overactive thyroid)
- T3 toxicosis
- Certain thyroid nodules or thyroid hormone resistance
2. Low FT3 levels may suggest:
- Hypothyroidism (underactive thyroid)
- Non-thyroidal illness syndrome (also known as sick euthyroid syndrome)
3. Normal FT3 levels alongside abnormal TSH or T4 results can help narrow down the type or stage of thyroid dysfunction.
Accurate interpretation of FT3 results is most effective when combined with TSH and Free T4 testing, providing a full picture of thyroid function and guiding appropriate treatment.