Thyroid Function Test (TFT)
A Thyroid Function Test (TFT) is a blood test used to assess the function of the thyroid gland, which is responsible for producing thyroid hormones that regulate metabolism and other bodily functions. TFTs typically measure levels of thyroid stimulating hormone (TSH), total thyroxine (T4), and total triiodothyronine (T3), as well as free T4 and free T3 (unbound hormones available for use in the body). These tests help diagnose and monitor conditions like hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid).
Purpose:
TFTs are used to evaluate thyroid health, diagnose thyroid disorders, and monitor the effectiveness of treatment.
What it measures:
- TSH: A hormone produced by the pituitary gland that stimulates the thyroid to release thyroid hormones.
- T4 (Thyroxine): A precursor to T3, indicating the thyroid's hormone production capacity.
- T3 (Triiodothyronine): The active thyroid hormone.
- Free T4 and Free T3: Unbound thyroid hormones readily available for use by the body.
Why it's important:
Abnormal TFT results can indicate:
- Hypothyroidism: Insufficient thyroid hormone production, leading to symptoms like fatigue, weight gain, and constipation.
- Hyperthyroidism: Excessive thyroid hormone production, resulting in symptoms like increased heart rate, weight loss, and anxiety.
How it's performed:
- A blood sample is drawn and sent to a laboratory for analysis. The results are typically available within 1-3 days.
Who might need a TFT:
- Individuals experiencing symptoms of thyroid disorders, those with a family history of thyroid problems, or those being monitored for treatment of thyroid conditions.