Thyroid Stimulating Hormone (TSH) Blood Test

Thyroid Stimulating Hormone (TSH) Blood Test

What Is a TSH Blood Test and Why Is It Done?

A thyroid stimulating hormone (TSH) blood test measures the amount of TSH in the blood. TSH is a hormone made by the pituitary, a pea-sized gland at the base of the brain.

Doctors order TSH tests to:

• diagnose thyroid disorders
• monitor treatment of thyroid gland problems
• see how well the thyroid or pituitary gland is working

TSH tests are usually included in newborn screening tests in most states. This is because congenital hypothyroidism, when a baby’s thyroid gland isn’t working as it should, can cause serious problems if it isn’t treated right away.

Top Things to Know

• The thyroid stimulating hormone (TSH) test checks the levels of a hormone in the blood called TSH.
• The test can help show how the thyroid and pituitary glands are working and check how any treatment is working.
• Kids might need to stop taking certain medicines or not eat or drink before the blood test.
• Your doctor can explain what it means if TSH levels are too low or too high.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a place that makes your child feel safe and relaxed can help.

What Do TSH Test Results Mean?

Your doctor will explain what the results of the TSH test mean for your child. What’s “normal” varies based on things like age and gender.

High TSH

When the thyroid gland doesn’t make enough of two important hormones, triiodothyronine (T3) and thyroxine (T4), it’s called hypothyroidism, or an underactive thyroid. In response, the pituitary gland makes more TSH to try to stimulate the thyroid so it’ll make more hormones. A pituitary gland that’s not working well can make too little TSH, which also can lead to hypothyroidism.

A high TSH level can be due to things like congenital hypothyroidism or Hashimoto's thyroiditis (hah-she-MOE-toes thy-roy-DYE-tiss), where the immune system attacks the thyroid.

Low TSH

If the thyroid gland makes too much T3 or T4, it can cause hyperthyroidism, or an overactive thyroid. Then, the pituitary gland makes less TSH to try to decrease the amount of hormones the thyroid makes.

A low TSH level is usually due to:

• Graves' disease
• thyroid gland inflammation (thyroiditis)
• thyroid nodules (growths in the thyroid gland)

What Else Should I Know?

When kids have a TSH blood test, they’ll likely have other thyroid blood tests too, like ones that measure the hormones T3 and T4.

Tell the doctor about any medicines your child takes because some can affect TSH test results. If you have questions about the TSH test or what the results mean, talk to your doctor.