målkörtelhormon

Målkörtelhormon, also known as thyroid-stimulating hormone (TSH) or thyrotropin, is a hormone produced by the anterior pituitary gland. Its primary function is to regulate the production and secretion of hormones by the thyroid gland. TSH stimulates the thyroid gland to synthesize and release thyroxine (T4) and triiodothyronine (T3), which are crucial for regulating metabolism, growth, and development in the body.

The release of TSH is controlled by a feedback loop involving the hypothalamus and the thyroid gland. The hypothalamus secretes thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to produce TSH. In turn, high levels of T4 and T3 in the bloodstream inhibit the release of both TRH and TSH, while low levels stimulate their release. This negative feedback mechanism ensures that thyroid hormone levels are maintained within a narrow physiological range.

Measuring TSH levels in the blood is a common diagnostic tool for thyroid disorders. High TSH levels typically indicate hypothyroidism, where the thyroid gland is underactive and not producing enough thyroid hormones. Low TSH levels, on the other hand, usually suggest hyperthyroidism, where the thyroid gland is overactive and producing too much thyroid hormone. TSH testing is therefore essential for diagnosing and monitoring conditions such as goiter, thyroid nodules, and autoimmune thyroid diseases like Hashimoto's thyroiditis and Graves' disease.