Which of the following is NOT a cause of hypercalcemia?

Chronic kidney disease (CKD) is generally associated with hypocalcemia rather than hypercalcemia. In CKD, the kidneys have a reduced ability to excrete phosphate, leading to hyperphosphatemia, which in turn can cause a decrease in serum calcium levels due to the inverse relationship between calcium and phosphate. Additionally, as renal function declines, the kidneys cannot produce adequate amounts of activated vitamin D (calcitriol), resulting in decreased intestinal absorption of calcium.

In contrast, vitamin D intoxication can lead to hypercalcemia by increasing calcium absorption from the gastrointestinal tract. Prolonged immobilization causes increased bone resorption and release of calcium into the bloodstream, thereby contributing to hypercalcemia. Hyperparathyroidism results in excess secretion of parathyroid hormone, which mobilizes calcium from bones and increases renal tubular reabsorption of calcium, leading to elevated serum calcium levels.

Thus, while the other conditions listed are linked to hypercalcemia, chronic kidney disease is primarily associated with lower calcium levels due to its effects on calcium metabolism and balance.