Free triiodothyronine (Free T3) (Free Triiodothyronine, FT3, Serum)
The test determines the concentration of free triiodothyronine (T3) — the biologically active thyroid hormone. Free T3 governs metabolic rate, thermoregulation, cardiovascular and nervous system function. Used for hyperthyroidism and thyrotoxicosis diagnosis and to clarify thyroid functional state. Recommended for palpitations, sweating, weight loss, irritability, tremor.
What the test evaluates:
- Free triiodothyronine level in blood serum
- Thyroid gland hormonal function activity
Biomaterial: Venous blood (serum)
- Draw blood fasting
- Exclude intense physical activity and stress 24 hours before
Medications:
- If possible, do not take thyroid hormones 24-48 hours before (consult physician)
- Iodine preparations and biotin may affect results
- Inform physician of all medications taken
Recommended for:
- Thyroid gland diseases
- Hormonal imbalance symptoms
- Tachycardia and arrhythmias
- Menstrual cycle disorders
Elevated free T3: may indicate hyperthyroidism or thyrotoxicosis
Reduced free T3: may indicate hypothyroidism or thyroid dysfunction
Note: Combination with TSH and T4 required for accurate interpretation; endocrinologist consultation mandatory.