PTHrP is produced by some cancers and often leads to cancer-associated hypercalcemia.

PTHrP is produced by some cancers and often leads to cancer-associated hypercalcemia.

• A. True
• B. False
• C. Not commonly
• D. Rarely

Answer: (A)

PTHrP from certain cancers raises calcium by acting on the same receptors as parathyroid hormone in bone and kidney. This stimulates osteoclast activity, increasing bone resorption, and enhances renal calcium reabsorption, pushing calcium levels upward. This mechanism, known as humoral hypercalcemia of malignancy, is a well-established and common cause of cancer-associated hypercalcemia. Because the calcium is high, the body's own parathyroid glands reduce PTH production, so PTH is typically low or suppressed while PTHrP remains elevated from the tumor. Many cancers can do this, especially squamous cell carcininomas of the lung and head and neck, among others. Thus, the statement is true.

PTHrP from certain cancers raises calcium by acting on the same receptors as parathyroid hormone in bone and kidney. This stimulates osteoclast activity, increasing bone resorption, and enhances renal calcium reabsorption, pushing calcium levels upward. This mechanism, known as humoral hypercalcemia of malignancy, is a well-established and common cause of cancer-associated hypercalcemia. Because the calcium is high, the body's own parathyroid glands reduce PTH production, so PTH is typically low or suppressed while PTHrP remains elevated from the tumor. Many cancers can do this, especially squamous cell carcininomas of the lung and head and neck, among others. Thus, the statement is true.