TSH (Thyroid-stimulating hormone) Test

What is TSH (Thyroid-Stimulating Hormone) Test?

The TSH (Thyroid-Stimulating Hormone) test is a laboratory test used to measure the amount of TSH in a person's blood. TSH is a hormone produced by the pituitary gland that helps control thyroid hormone production in the body. TSH stimulates the thyroid gland to produce and release two hormones–Triiodothyronine (T3) and Thyroxine (T4). Low or high levels of TSH can indicate that the thyroid is not functioning properly.

Preparation for TSH Test

You don't need any special preparation for this test. Your healthcare provider will give you specific instructions on what to do before the test. Generally, it's a good idea to fast for 8-12 hours before the test as food and drinks may affect the accuracy of the results.

Procedure of TSH Test

The procedure involves drawing a sample of blood from a vein in your arm. The laboratory technician will clean the area, then insert a needle into your arm to draw blood. The blood sample is then sent to a lab for testing.

Types of TSH Test

  • Free T4 Test: This test measures the amount of free T4 in the blood. Free T4 is a form of T4 that is not bound to other molecules and is available for use by the body.
  • T3 Test: This test measures the amount of T3 in the blood. T3 is an active form of thyroid hormone that is naturally produced by the thyroid gland.
  • Total T4 Test: This test measures the amount of total T4 in the blood. Total T4 is the amount of T4 bound to other molecules in the blood.
  • Thyroglobulin (Tg) Test: This test measures the amount of thyroglobulin (Tg) in the blood. Tg is a protein produced by the thyroid gland.
  • Thyroid Stimulating Hormone Receptor Antibodies Test: This test measures the levels of thyroid stimulating hormone receptor antibodies in the blood. These antibodies can interfere with the normal functioning of TSH.

Risks of TSH Test

The risks of a TSH test are minimal. The most common risks associated with this test are those associated with having your blood drawn, such as:

  • Fainting
  • Lightheadedness
  • Infection
  • Swelling
  • Bruising at the puncture site

Why Get a TSH Test?

The TSH test is used to evaluate thyroid function. It is usually ordered when someone has signs or symptoms of a thyroid disorder, such as:

  • Fatigue
  • Weight gain/loss
  • Changes in heart rate or blood pressure
  • Changes in hair, skin, or nails
  • Irritability or mood changes
  • Difficulty concentrating

The TSH test can also be used to monitor the effectiveness of treatment for a thyroid disorder or to assess the risk of developing thyroid-related diseases such as hyperthyroidism and hypothyroidism.

When to Get a TSH Test?

Your healthcare provider may order a TSH test if you have signs and symptoms of a thyroid disorder, if you are pregnant, or if you are starting a new medication. They may also order this test if you have had previous thyroid surgery or thyroid cancer.


TSH tests are an important tool in evaluating thyroid function and detecting thyroid disorders. The test is relatively safe and is generally done as an outpatient procedure with minimal risks.