Thyroid Stimulating Hormone
Does this test have other names?
TSH, thyrotropin test
What is this test?
This is a blood test that measures your level of thyroid stimulating hormone (TSH). Healthcare providers use this test to diagnose problems affecting the thyroid.
Your thyroid is a butterfly-shaped gland near the base of your throat above your collarbones. The thyroid makes 2 hormones, T3 and T4. These hormones affect your energy levels, mood, weight, and other important parts of your health.
The pituitary gland in your brain makes a chemical called TSH. TSH triggers your thyroid to make T3 and T4. When your pituitary gland makes too much or too little TSH, this can cause your thyroid to be overactive (hyperthyroidism) or underactive (hypothyroidism).
Why do I need this test?
You may need this test if you have symptoms of thyroid problems.
Symptoms of hyperthyroidism include:
Anxiety and mood swings
Weakness in the arms and legs
Low tolerance for heat
Unexplained weight loss
More frequent bowel movements than usual
Eye irritation or bulging eyes, which are symptoms of Graves disease, a common cause of hyperthyroidism
Enlarged breasts and erectile dysfunction in men
Symptoms of hypothyroidism include:
Low tolerance for cold
Slower heart rate
Shortness of breath
Loss of consciousness, although this is rare
Healthcare providers may also check TSH levels when diagnosing depression and dementia.
What other tests might I have along with this test?
You may have tests to check your levels of:
Thyroglobulin, which helps produce and store thyroid hormones
TSH receptor-stimulator antibodies, which is used to diagnose Graves disease
Thyroid antiperoxidase antibodies and thyroglobulin antibodies, to diagnose Hashimoto's thyroiditis
What do my test results mean?
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
Low TSH may mean you have hyperthyroidism. High TSH can mean you have hypothyroidism. The results of other thyroid tests can help to find the cause.
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Some medicines keep the pituitary gland from releasing TSH. These include:
Other medicines that can affect thyroid tests include:
How do I get ready for this test?
Tell your healthcare provider if you're taking medicine. Certain medicines can affect thyroid test results.
Be sure your provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.