The Free T4 (FT4) test measures the level of unbound thyroxine (T4) hormone in the blood. T4 is produced by the thyroid gland and plays a vital role in regulating metabolism and growth.

This test specifically evaluates the free (biologically active) form of thyroxine, which is not bound to proteins and can directly affect body cells. It helps in diagnosing thyroid disorders such as hypothyroidism and hyperthyroidism, and in monitoring treatment effectiveness in patients with known thyroid conditions.

Orange Health Labs provides convenient at-home sample collection for Free T4 tests across multiple cities, with rapid report delivery.

The cost of the Free T4 test is generally around ₹350, though it may vary depending on the city where the order is placed. Prices include home collection.

No special preparation is needed for the Free T4 test. Fasting is not required.

Who Should Get This Test?

• Individuals with symptoms of thyroid dysfunction

• Patients with abnormal TSH results

• Those on thyroid hormone therapy

• Pregnant women with thyroid conditions

During the Test:

A healthcare professional will draw a blood sample from a vein in your arm The collection process typically takes less than 5 minutes

After the Test:

• Mild bruising or discomfort may occur

• Samples are sent to the lab, and results are usually available within 6 hours

Your doctor may recommend a Free T4 (FT4) test if you show signs of an underactive or overactive thyroid or have abnormal TSH levels.

Signs of Hyperthyroidism (Overactive Thyroid):

• Rapid heartbeat

• Anxiety and insomnia

• Weight loss

• Tremors or shakiness

• Heat sensitivity and excessive sweating

• Visual disturbances or bulging eyes

• Menstrual irregularities

Signs of Hypothyroidism (Underactive Thyroid):

• Weight gain

• Fatigue

• Cold intolerance

• Constipation and dry skin

• Hair thinning or loss

• Puffy skin

• Irregular periods

The FT4 test is also used in pregnancy and to monitor ongoing thyroid treatment.

Free T4 test results help determine thyroid function and guide diagnosis when interpreted with other tests such as TSH.

Normal Reference Range:

Free T4 : 0.78–2.19 ng/dL

Interpretation Guide:

• High FT4: May indicate hyperthyroidism (overactive thyroid), often due to Graves' disease or thyroiditis

• Low FT4: May indicate hypothyroidism (underactive thyroid), often linked to Hashimoto's thyroiditis or pituitary dysfunction

FT4 levels should always be interpreted in conjunction with TSH and clinical symptoms.

Additional testing may include:

• Thyroid Function Test

• TSH (Thyroid Stimulating Hormone)

• TPO (Thyroid Peroxidase Antibody)