kõrvalkilpnäärmeid

Kõrvalkilpnäärmed are small endocrine glands located in the neck, typically behind or very close to the thyroid gland. Humans usually have four such glands, arranged in two pairs, superior and inferior, though variations in number and location can occur. These glands are crucial for regulating calcium and phosphate levels in the body.

The primary function of the parathyroid glands is the secretion of parathyroid hormone (PTH). PTH plays a vital role in maintaining calcium homeostasis. When blood calcium levels drop too low, the parathyroid glands release PTH, which acts on several target organs. It stimulates the kidneys to reabsorb calcium, preventing its loss in urine, and also promotes the release of calcium from bones. Additionally, PTH influences the intestines to absorb more calcium from food by stimulating the production of active vitamin D.

Conversely, when blood calcium levels are sufficiently high, PTH secretion is suppressed, reducing calcium reabsorption and bone resorption. This finely tuned regulation ensures that calcium levels remain within a narrow, healthy range, which is essential for numerous physiological processes, including nerve function, muscle contraction, and blood clotting. Disruptions in parathyroid gland function can lead to either hyperparathyroidism, characterized by excessive PTH production and high blood calcium levels, or hypoparathyroidism, where PTH production is insufficient, resulting in low blood calcium levels.