What can lead to hypercalcemia, affecting calcium metabolism?

Hyperparathyroidism is a condition characterized by the overproduction of parathyroid hormone (PTH) by the parathyroid glands. PTH plays a critical role in regulating calcium levels in the bloodstream by promoting the release of calcium from bones, increasing kidney reabsorption of calcium, and enhancing intestinal absorption of calcium through its effects on vitamin D metabolism. When there is an excess of PTH due to hyperparathyroidism, it leads to increased levels of calcium in the blood, a condition known as hypercalcemia.

This metabolic disturbance can result in various clinical manifestations, including symptoms such as fatigue, weakness, depression, constipation, and kidney issues. Detection of hypercalcemia involves measuring serum calcium levels, and hyperparathyroidism is one of the most common causes of elevated calcium levels in patients.

Other conditions listed, such as hypoparathyroidism, cirrhosis, and polycythemia, typically do not lead to an increase in calcium levels. Hypoparathyroidism is marked by insufficient PTH production, resulting in lower calcium levels. Cirrhosis may affect various metabolic processes but typically does not directly lead to hypercalcemia. Polycythemia involves an increased red blood cell mass and is not related