What is a characteristic lab finding in patients with hyperparathyroidism?

In hyperparathyroidism, one of the hallmark laboratory findings is hypercalcemia, which is an elevated level of calcium in the blood. This condition arises due to the overproduction of parathyroid hormone (PTH), which plays a critical role in calcium homeostasis. When PTH levels are high, they stimulate the release of calcium from bones, increase intestinal absorption of calcium from food, and enhance the reabsorption of calcium in the kidneys. The combined effects of these mechanisms lead to an increase in serum calcium levels.

Additionally, hyperparathyroidism can also be associated with changes in phosphate levels. Typically, patients may experience mild hypophosphatemia, but this is not as definitive or characteristic as hypercalcemia. Hypocalcemia and hypermagnesemia would not be associated with hyperparathyroidism, as the condition inherently leads to increased calcium levels.

This understanding highlights how hyperparathyroidism disrupts the normal regulatory mechanisms of calcium, making hypercalcemia a key lab finding in diagnosing and managing the condition.