Thyroid Function Tests (TFTs)
Thyroid function tests (TFTs) are a group of blood tests used to evaluate the function of the thyroid gland, which is a vital endocrine gland located in the neck. These tests help assess various aspects of thyroid function and can aid in the diagnosis and management of thyroid disorders. The thyroid gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3), which regulate metabolism and various physiological functions in the body. TSH is produced by the pituitary gland and stimulates the thyroid gland to produce T4 and T3. High levels of TSH typically indicate hypothyroidism (underactive thyroid), while low levels may suggest hyperthyroidism (overactive thyroid). Thyroid function tests are commonly used to diagnose and monitor various thyroid conditions, including:
- Hypothyroidism: Characterized by low levels of thyroid hormones, hypothyroidism can cause symptoms such as fatigue, weight gain, cold intolerance, and constipation.
- Hyperthyroidism: Marked by high levels of thyroid hormones, hyperthyroidism can lead to symptoms such as weight loss, palpitations, heat intolerance, anxiety, and tremors.
- Thyroid nodules: TFTs may be used to evaluate thyroid nodules, which are growths or lumps in the thyroid gland. Additional imaging and biopsy may be needed to determine if a nodule is benign or malignant.
- Thyroid antibodies: In autoimmune thyroid disorders such as Hashimoto's thyroiditis and Graves' disease, the immune system produces antibodies that attack the thyroid gland. Tests for thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) can help diagnose these conditions.
- Thyroid cancer: Thyroid function tests may be part of the evaluation for thyroid cancer, though they are not diagnostic for cancer itself. Fine-needle aspiration biopsy and imaging studies are typically used for diagnosis and staging.