What is Thyroid Stimulating Hormone Test (TSH)

Why am I having this test?

Thyroid stimulating hormone test is done if you have possible symptoms of abnormal thyroid hormone levels. This test can help your health care provider:

• Diagnose a disorder of the thyroid gland or pituitary gland.
• Manage your condition and treatment if you have an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism).

Newborn babies may have this test done to screen for hypothyroidism that is present at birth (congenital).

The thyroid is a gland in the lower front of the neck. It makes hormones that affect many body parts and systems, including the system that affects how quickly the body burns fuel for energy (metabolism). The pituitary gland is located just below the brain, behind the eyes and nasal passages. It helps maintain thyroid hormone levels and thyroid gland function.

What is being tested?

This test measures the amount of TSH in your blood. TSH may also be called thyrotropin. When the thyroid does not make enough hormones, the pituitary gland releases TSH into the bloodstream to stimulate the thyroid gland to make more hormones.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel. For newborns, a small amount of blood may be collected from the umbilical cord, or by using a small needle to prick the baby’s heel (heel stick).

Tell a health care provider about:

• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any blood disorders you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.

How are the results reported?

Your test results will be reported as a value that indicates how much TSH is in your blood. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Adult: 2–10 microunits/mL or 2–10 milliunits/L.
• Newborn:
  • Heel stick: 3–18 microunits/mL or 3–18 milliunits/L.
  • Umbilical cord: 3–12 microunits/mL or 3–12 milliunits/L.

What do the results mean?

Results that are within the reference range are considered normal. This means that you have a normal amount of TSH in your blood.

Results that are higher than the reference range mean that your TSH levels are too high. This may mean:

• Your thyroid gland is not making enough thyroid hormones.
• Your thyroid medicine dosage is too low.
• You have a tumor on your pituitary gland. This is rare.

Results that are lower than the reference range mean that your TSH levels are too low. This may be caused by hyperthyroidism or by a problem with the pituitary gland function.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• You may have a thyroid-stimulating hormone (TSH) test if you have possible symptoms of abnormal thyroid hormone levels.
• The thyroid is a gland in the lower front of the neck. It makes hormones that affect many body parts and systems.
• The pituitary gland is located just below the brain, behind the eyes and nasal passages. It helps maintain thyroid hormone levels and thyroid gland function.
• This test measures the amount of TSH in your blood. TSH is made by the pituitary gland. It may also be called thyrotropin.