Patient education: Thyroid-stimulating hormone test (The Basics)

What is a thyroid-stimulating hormone test? — A thyroid-stimulating hormone test is a type of blood test. It measures the amount of thyroid-stimulating hormone, or "TSH," in the blood.

TSH is made in the pituitary gland. The pituitary gland is a small organ found at the base of the brain (figure 1). It controls all of the other glands in the body, including the thyroid gland. TSH tells the thyroid to release thyroid hormones. These hormones control how the body uses and stores energy (figure 2).

If your thyroid is making too little or too much thyroid hormone, your pituitary gland tries to correct this by making more or less TSH. Your TSH level can show if you have a problem with your thyroid gland. It can also show if there is a problem with the pituitary gland itself.

Why might I get a TSH test? — Reasons that your doctor or nurse might want you to have a TSH test include:

●If you have symptoms of a thyroid problem, like:

•Hypothyroidism – This is when the thyroid makes too little thyroid hormone. Symptoms can include feeling tired or weak, getting cold easily, thinning hair, weight gain, and constipation.

•Hyperthyroidism – This is when the thyroid makes too much thyroid hormone. Symptoms can include anxiety, trouble sleeping, shaking or sweating, and weight loss.

●To see how your thyroid is working if you are at risk for thyroid disease

●To see if treatment for a thyroid problem is working

●To check for problems with your pituitary gland

How do I prepare for a TSH test? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 3). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or, if you use an online "patient portal," you might get an alert there when your results are ready.

If your TSH test shows any abnormal results, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics)
Patient education: Hyperthyroidism (overactive thyroid) (The Basics)
Patient education: Thyroiditis (The Basics)
Patient education: Graves' disease (The Basics)
Patient education: Panhypopituitarism (The Basics)

Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics)
Patient education: Hyperthyroidism (overactive thyroid) (Beyond the Basics)