A patient with hyperparathyroidism is being evaluated for treatment options. Which of the following findings would most likely be present in this patient related to calcium metabolism?

Rationale: A. Hyperparathyroidism is characterized by overproduction of parathyroid hormone (PTH). PTH stimulates osteoclast activity, which breaks down bone tissue and releases calcium into the bloodstream, leading to hypercalcemia. Other effects of elevated PTH include increased renal calcium reabsorption and enhanced activation of vitamin D, which further increases intestinal calcium absorption. B. In hyperparathyroidism, PTH promotes conversion of vitamin D to its active form (calcitriol), which enhances intestinal absorption of calcium rather than decreasing it. Low intestinal calcium absorption is more associated with vitamin D deficiency, not primary hyperparathyroidism. C.PTH actually increases renal calcium reabsorption in the distal tubules. Decreased reabsorption would result in calcium loss and hypocalcemia, which is opposite of what occurs in hyperparathyroidism. D. PTH is elevated in hyperparathyroidism, not low. Increased calcium excretion (hypercalciuria) can occur secondary to extremely high serum calcium levels, but it is not due to low PTH.