Test is included in the Thyroid Panel II

?? Third-generation TSH; Thyrotropin; TSH

Why It Is Done

Determine whether the thyroid gland is functioning properly.
Screen for underactive thyroid gland (hypothyroidism)
Screen for overactive thyroid (hyperthyroidism)
Determine the cause of an underactive thyroid gland (hypothyroidism).
Monitor treatment with thyroid replacement medications for people who have hypothyroidism.
Monitor thyroid gland function in people who are being treated for hyperthyroidism
Who Should Be Tested

Opinions vary on who can benefit from screening and at what age to begin. The American Thyroid Association recommends the following:

The American Association of Clinical Endocrinologists advises the following:

If you have symptoms or risk factors, no matter what your age or sex, getting tested is appropriate. For other adults, be alert that what you assume to be natural signs of aging may possibly be a thyroid problem.

Test Overview Thyroid disease is more common than diabetes or heart disease. Many people have underactive or overactive thyroids but do not know it because the symptoms are vague: fatigue, mood swings, forgetfulness, weight gain, depression, even dry and coarse skin and hair. A problem in this hormone-producing gland can affect every system and cell in your body, leaving you vulnerable to heart disease, osteoporosis, and other illnesses.

About 1 in 8 American women will develop a thyroid disorder. An underactive thyroid (hypothyroidism) is more common in women than men and often hits hardest during pregnancy, midlife, and older age.

A thyroid-stimulating hormone (TSH) blood test is used to detect problems affecting the thyroid gland. 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 produce two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your body's metabolism.

The brain regulates the amount of thyroid hormones in the blood. When the hormone levels are low, the brain sends a message to send out TSH. This causes the thyroid gland to send out more hormones. If blood levels of thyroid hormone are high, the brain senses this and sends a message to stop producing TSH. TSH is a very good test to check for hypothyroidism. TSH is increased with hypothyroid and decreased with hyperthyroid.

This test may be done at the same time as tests to measure T3 and T4.

How To Prepare

No special preparation is necessary. "