TSH (THYROID STIMULATING HORMONE)

The TSH test (Thyroid-Stimulating Hormone test) is a blood test that measures the level of thyroid-stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland and plays a crucial role in regulating the thyroid gland, which controls metabolism, energy levels, and overall body function by producing the hormones triiodothyronine (T3) and thyroxine (T4).

The TSH test is primarily used to:

1. Diagnose thyroid disorders, such as:
   • Hypothyroidism (underactive thyroid), where TSH levels are elevated as the pituitary gland signals the thyroid to produce more hormones.
   • Hyperthyroidism (overactive thyroid), where TSH levels are low as the pituitary reduces signals to an overactive thyroid.
2. Monitor thyroid treatment, especially for patients taking medication for thyroid conditions. It helps ensure that treatment is keeping hormone levels within a healthy range.

Normal TSH levels typically range between 0.4 to 4.0 milliunits per liter (mU/L), though these ranges may vary slightly based on the laboratory and individual health conditions.

This test is commonly ordered when patients present symptoms like unexplained weight changes, fatigue, mood disturbances, or changes in heart rate, which may suggest a thyroid imbalance. It can also be part of routine health screenings. Based on TSH levels, further tests like T3 and T4 may be ordered to get a clearer picture of thyroid function.