A TSH test measures the amount of thyroid-stimulating hormone (TSH) in your blood. TSH is a hormone produced by the pituitary gland, a small gland located at the base of your brain. Its primary function is to regulate the thyroid gland's production of thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). These thyroid hormones are crucial for numerous bodily functions, including metabolism, growth, and development.
Understanding the TSH Test
The TSH test is a simple blood test that is commonly used to assess thyroid function. By measuring the level of TSH in the blood, doctors can determine whether the thyroid gland is producing the correct amount of thyroid hormones.
- High TSH levels: Often indicate hypothyroidism (underactive thyroid), meaning the thyroid isn't producing enough hormones. The pituitary gland attempts to compensate by producing more TSH.
- Low TSH levels: Can suggest hyperthyroidism (overactive thyroid), where the thyroid is producing too much hormones. In this case, the pituitary gland reduces TSH production.
The results of a TSH test are usually measured in milliunits per liter (mU/L). A normal range varies slightly depending on the laboratory, but typically falls within a specific range. Your doctor will interpret your results in relation to this reference range and your individual medical history.
Several reputable sources, including MedlinePlus (https://medlineplus.gov/lab-tests/tsh-thyroid-stimulating-hormone-test/), Mount Sinai (https://www.mountsinai.org/health-library/tests/tsh-test), and the Mayo Clinic (https://www.mayoclinic.org/diseases-conditions/hypothyroidism/diagnosis-treatment/drc-20350289), confirm that a TSH test directly measures the level of thyroid-stimulating hormone in the blood. This test is a cornerstone in diagnosing thyroid disorders.
