The TSH (Thyroid-Stimulating Hormone) test is performed to evaluate thyroid function and diagnose disorders related to this gland. TSH is a hormone secreted by the pituitary gland that regulates the production of thyroid hormones (T3 and T4). TSH levels are inversely related to thyroid activity; meaning a high TSH level usually indicates hypothyroidism, as the body tries to increase thyroid hormone production by stimulating the thyroid gland more. Conversely, a low TSH level may indicate hyperthyroidism, since excess thyroid hormones suppress TSH secretion through a negative feedback mechanism. This test is done using a venous blood sample and is often used as the initial test in investigating thyroid disorders (along with T3 and T4). Interpretation of results must consider clinical factors, age, pregnancy, or medication use (such as Levothyroxine). Additionally, TSH plays a key role in monitoring the effectiveness of hormone replacement therapies or thyroid suppressants. Abnormal TSH levels may be associated with symptoms like fatigue, weight gain/loss, sensitivity to cold or heat, and changes in heart rate.
