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Home > Health Library > Thyroid-Stimulating Hormone (TSH) Test
A thyroid-stimulating hormone (TSH) blood test is used to check for thyroid gland problems. TSH is produced when the hypothalamus releases a substance called thyrotropin-releasing hormone (TRH). TRH then triggers the pituitary gland to release TSH.
TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your body's metabolism.
Triiodothyronine (T3) and thyroxine (T4) are needed for normal growth of the brain, especially during the first 3 years of life. A baby whose thyroid gland does not make enough thyroid hormone (congenital hypothyroidism) may, in severe cases, have below-average intelligence. Older children also need thyroid hormones to grow and develop normally.
This test may be done at the same time as tests to measure T3 and T4.
A test for thyroid-stimulating hormone (TSH) is done to:
In general, there's nothing you have to do before this test, unless your doctor tells you to.
A health professional uses a needle to take a blood sample, usually from the arm.
The test will take a few minutes.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
Results are usually available in 2 to 3 days.
A slightly high TSH value may not require treatment. The doctor will consider any symptoms you might have along with other test results to determine if treatment is needed.
High TSH levels may be caused by:
Low TSH levels may be caused by:
Current as of:
December 2, 2020
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineKathleen Romito MD - Family MedicineMatthew I. Kim MD - Endocrinology
Current as of: December 2, 2020
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Matthew I. Kim MD - Endocrinology
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