In monitoring thyroid function, which test is primarily used?

The primary test used in monitoring thyroid function is the TSH (Thyroid-Stimulating Hormone) test. TSH is produced by the pituitary gland and plays a crucial role in regulating the production of thyroid hormones from the thyroid gland. When the levels of thyroid hormones (T3 and T4) are low, the pituitary gland releases more TSH to stimulate the thyroid to increase hormone production. Conversely, when thyroid hormone levels are high, TSH production decreases.

By measuring TSH levels, healthcare professionals can assess how well the thyroid gland is functioning. High levels of TSH may indicate hypothyroidism, where the thyroid is underactive, while low levels of TSH can suggest hyperthyroidism, where the thyroid is overactive. Thus, TSH is considered the most reliable test for evaluating thyroid function.

Other tests mentioned, such as hcG (human chorionic gonadotropin), are primarily associated with pregnancy and not relevant to thyroid function. BUN (Blood Urea Nitrogen) is used to assess kidney function, while 2HPP (2-Hour Postprandial) usually measures glucose levels related to diabetes management. These tests do not provide insight into thyroid health, reinforcing the importance of T