Thyroid-Stimulating Hormone (TSH)

What is TSH?

TSH is produced by the pituitary gland and stimulates the thyroid to produce the hormones thyroxine (T4) and triiodothyronine (T3). The thyroid is a butterfly shaped gland that is found near your throat. It produces hormones that are needed to regulate your body’s energy usage. These hormones are also involved in managing your weight and keeping your temperature at a normal level. They also affect your mood and muscle strength. When too much or too little TSH is produced, it impacts the levels of other thyroid hormones. The TSH test can help detect if you have a thyroid disorder like hyperthyroidism or hypothyroidism.

Why take a TSH test?

The American Thyroid Association (ATA) recognizes TSH as the first test used to screen for and help detect thyroid conditions, such as hypothyroidism (under-active thyroid) or hyperthyroidism (over-active thyroid). TSH is also used to monitor existing thyroid conditions and the effectiveness of the treatments chosen.

According to the American Thyroid Association, about 12 percent of people in the US have a thyroid condition, and half of them are unaware. Thyroid conditions can affect anyone but are more common in women. It is estimated that one in eight women will have a thyroid problem at some point in their life. Sometimes, thyroid conditions are mistaken for menopause symptoms hence the need to get tested.

An underactive gland is normally treated by taking synthetic thyroid hormones, daily, which will bring the blood levels back to normal. As a result, you feel more energetic and can lose the weight may have you gained. In that case, your TSH levels will be tested every two months to make sure you are receiving the right treatment. If the results come back within normal ranges, your TSH will typically be checked once a year.

An overreactive thyroid is treated in various ways such as using radioactive iodine, anti-thyroid medications, beta blockers or surgically removing the gland. If you are diagnosed with an overactive thyroid you will need periodic TSH testing to monitor your levels.

What can cause TSH levels to rise?

You may want to keep in mind that certain medications and illnesses can influence your TSH levels. So, you may want to wait for your illness to pass before doing the test.

What your TSH test results mean?

Normally, your TSH levels should range between 1.4 and 4.0 milli-international units. If you have a thyroid condition and you are following a course of treatment; then your normal ranges would be between 0.3 and 3.0. Values above this range indicate an underactive gland while values below this range suggest an overactive gland.

Where can I get a TSH test near me?

Please use our Lab Locator to find find a convenient testing location.

References

1. American Thyroid Association. Thyroid Function Tests. Available at: https://www.thyroid.org/thyroid-function-tests/.
2. American Thyroid Association. General Information/About Hypothyroidism. Available at: https://www.thyroid.org/hypothyroidism/.

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Apr 17, 2019