Which condition can cause hypercalcemia?

Hyperparathyroidism is a condition that can lead to hypercalcemia due to the increased production of parathyroid hormone (PTH) by the parathyroid glands. PTH acts on the bones, kidneys, and intestines to increase calcium levels in the blood. In the bones, it promotes the release of calcium, while in the kidneys, it enhances calcium reabsorption and decreases phosphate reabsorption. Additionally, increased intestinal absorption of calcium occurs due to enhanced vitamin D metabolism stimulated by PTH.

In contrast, conditions such as thyroid storm, acute pancreatitis, and renal failure do not typically result in elevated calcium levels in a similar direct manner. Thyroid storm is associated with excessive thyroid hormone levels leading to symptoms such as increased metabolism and does not directly affect calcium metabolism significantly. Acute pancreatitis may cause hypocalcemia due to fat saponification but is not a common cause of hypercalcemia. Lastly, renal failure usually leads to hypocalcemia due to decreased activation of vitamin D and retention of phosphate, which can bind calcium, further lowering serum calcium levels.

Thus, hyperparathyroidism is the most straightforward and direct cause of hypercalcemia among the listed conditions.