What are they?

Thyroid hormone tests are blood tests that check to see how well your child's thyroid gland is working. The thyroid gland is a butterfly-shaped gland that lies in front of your child's windpipe (trachea). It's just below the voice box (larynx). The thyroid gland makes hormones that control the way your child's body uses energy (metabolism).

These tests show your child's thyroid hormone levels. Your child's thyroid may be making too much or too little hormone.

Why is this test done?

Thyroid hormone tests are done to find the cause of an abnormal thyroid-stimulating hormone (TSH) test. TSH tests can also check how well treatment for thyroid disease is working. They are used in newborns to find out if the thyroid gland is working as it should.

How do you prepare for the test?

If your child takes thyroid medicines, tell the doctor when your child took the last dose. Your child may need to stop taking thyroid medicines for a short time before having these tests. Extreme stress and illness can also affect thyroid test results.

How is the test done?

Blood test

A health professional uses a needle to take a blood sample, usually from the arm.

Heel stick

A heel stick is used to get a blood sample from a baby. The baby's heel is poked, and several drops of blood are collected. Your baby may have a tiny bruise where the heel was poked.

What happens after the test?

• Your child will probably be able to go home right away.
• Your child can go back to usual activities right away.