TRI-IODO THYRONINE(T3), SERUM

Tri-iodo Thyronine (T3), Serum

What it is

The Tri-iodo Thyronine (T3) test measures the level of T3 hormone in the blood. T3 is an active thyroid hormone that regulates metabolism, growth, and energy balance. It is produced in small amounts by the thyroid gland and mainly converted from thyroxine (T4) in the body.

Uses

This test helps in diagnosing and monitoring thyroid disorders, differentiating between hyperthyroidism and hypothyroidism, evaluating metabolic imbalances, and checking response to thyroid hormone replacement therapy.

Symptoms That May Lead to the Test

Hyperthyroidism (High T3): Weight loss despite good appetite, heat intolerance, sweating, tremors, palpitations, anxiety, irritability, and enlarged thyroid (goiter).

Hypothyroidism (Low T3): Fatigue, weakness, weight gain, cold intolerance, dry skin, hair loss, depression, slow heart rate, and sluggishness.

Abnormal Results

High T3: Seen in hyperthyroidism (Graves’ disease, toxic nodular goiter), early thyroiditis, or excess thyroid hormone therapy.

Low T3: Indicates hypothyroidism, severe illness (euthyroid sick syndrome), chronic liver disease, malnutrition, or drug effects (steroids, amiodarone).

Risks

This is a routine blood test with minimal risks. Possible side effects include mild pain, bruising, or bleeding at the puncture site, and rarely dizziness or infection.