What is a common cause of hypercalcemia?

• A. Hypoparathyroidism
• B. Rickets
• C. Malignancy
• D. Kidney failure

Answer: (C)

Hypercalcemia, which is an elevated level of calcium in the blood, can result from various underlying conditions. Among these, malignancy is a common and significant cause. Many cancers, particularly those of the lung, breast, and multiple myeloma, can lead to hypercalcemia through different mechanisms. One primary mechanism is the secretion of parathyroid hormone-related peptide (PTHrP) by tumors, which mimics the action of parathyroid hormone and increases calcium release from bones, increases renal tubular reabsorption of calcium, and promotes intestinal absorption of calcium.

Additionally, some tumors can cause local osteolysis (bone breakdown) due to the invasion of cancer cells, further contributing to elevated serum calcium levels. Therefore, malignancy is recognized as a major contributor to hypercalcemia, making it the correct answer for this question.

In contrast, hypoparathyroidism generally leads to hypocalcemia due to insufficient parathyroid hormone secretion. Rickets, which is primarily due to vitamin D deficiencies, can lead to weak bones and may result in low calcium levels as well. Kidney failure may also lead to disturbances in calcium metabolism, often resulting in lower calcium levels due to impaired activation of vitamin D, although in certain