Tyrotropiini

Tyrotropiini, also known as thyrotropin or thyroid-stimulating hormone (TSH), is a glycoprotein hormone produced by the anterior pituitary gland. Its primary function is to regulate the production and secretion of thyroid hormones, namely thyroxine (T4) and triiodothyronine (T3), by the thyroid gland. TSH exerts its effects by binding to TSH receptors located on the surface of thyroid follicular cells. This binding triggers a cascade of intracellular events that lead to increased iodine uptake, synthesis, and release of thyroid hormones.

The secretion of TSH is tightly regulated by the hypothalamic hormone thyrotropin-releasing hormone (TRH) and the negative feedback effect of circulating thyroid hormones. TRH, released from the hypothalamus, stimulates TSH production and release from the pituitary. Conversely, elevated levels of T4 and T3 suppress TRH and TSH secretion. This feedback loop ensures that thyroid hormone levels in the bloodstream are maintained within a narrow physiological range.

Measurement of TSH levels in blood is a common diagnostic tool for assessing thyroid function. High TSH levels typically indicate hypothyroidism (underactive thyroid), where the thyroid gland is not producing enough thyroid hormones. Low TSH levels, on the other hand, often suggest hyperthyroidism (overactive thyroid), where the thyroid gland produces too much thyroid hormone. Tyrotropiini plays a crucial role in maintaining metabolic homeostasis throughout the body, influencing processes such as growth, development, and energy expenditure.