Thyroid Overview

Thyroid Function Tests

What is the Thyroid Gland?

The thyroid gland is located on the front surface of the neck and produces essential hormones daily.

Its Functions Include:

  • Regulating metabolism

  • Controlling the function of cardiovascular and nervous systems

  • Maintaining body temperature

  • Preserving muscle strength

If the thyroid gland does not produce enough hormones, hypothyroidism develops. Conversely, if it releases an excessive amount of hormones, hyperthyroidism occurs.

Functional Tests

Thyroid function tests are performed to diagnose hypo- or hyperthyroidism by measuring thyroid hormone concentrations in the blood.

Most Common Blood Tests

  • TSH (Thyroid-Stimulating Hormone): Produced in the brain, specifically in the pituitary gland, TSH regulates thyroid activity. Initially, this test is conducted, where a high TSH level indicates hypothyroidism, while a low level suggests hyperthyroidism.

  • FT4 (Thyroxine): Usually tested alongside TSH. A low TSH and high FT4 indicate hyperthyroidism, whereas a high TSH and low FT4 suggest hypothyroidism.

  • FT3 (Triiodothyronine): Often used to diagnose hyperthyroidism or assess its severity. (Sometimes, TSH is low while FT4 remains normal). A high T3 level indicates hyperthyroidism.

Other Blood Tests

Typically, antibodies are produced by the immune system to protect against diseases and infections. However, in some cases, these antibodies malfunction and damage thyroid tissue, altering thyroid function. High antibody levels indicate an autoimmune thyroid disorder.

  • Thyroglobulin Test: This test does not assess thyroid function but measures the amount of thyroglobulin protein in the blood. This protein is produced by a normal thyroid gland. It is primarily used to monitor patients who have undergone thyroid surgery due to thyroid cancer.

Other Diagnostic Methods

  • Radioactive Iodine Uptake Test: In this procedure, the patient takes a small oral dose of radioactive iodine, and the doctor evaluates its uptake. This test helps determine the cause of hyperthyroidism.

  • Thyroid Ultrasound Examination: During the procedure, safe ultrasound waves are used to obtain structural images of the thyroid gland. These images help doctors assess thyroid nodules, their size, and composition (fluid-filled/cystic or tissue-based). The procedure is painless and takes about 30 minutes.

  • Fine-Needle Aspiration Biopsy: If necessary, the doctor may recommend a biopsy. In this procedure, a thin needle extracts a sample of cells from a thyroid nodule for microscopic examination. Most patients compare the experience to receiving a regular injection.

Post-Biopsy Recommendations

If you experience mild pain at the biopsy site, you may take a pain reliever (e.g., ibuprofen) or consult your doctor for specific recommendations. Most patients do not require pain medication. If discomfort arises, you can apply ice locally for 10-15 minutes.

Test Results

In most cases, test results are available within two days after the procedure.

When to Contact a Doctor

Seek medical attention if you experience:

  • Increasing pain that does not respond to pain relievers

  • Dizziness or fainting

  • Difficulty swallowing

  • Excessive sweating around the neck

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