Which statement best describes CKD-related secondary hyperparathyroidism?

Which statement best describes CKD-related secondary hyperparathyroidism?

• A. PTH is suppressed due to phosphate retention
• B. PTH remains within normal range
• C. PTH is elevated due to parathyroid hyperplasia and hypocalcemia
• D. PTH becomes undetectable

Answer: (C)

In CKD, the balance of calcium and phosphate is disrupted, and that disruption drives secondary hyperparathyroidism. The failing kidneys can’t excrete phosphate effectively, so phosphate builds up in the blood. High phosphate promotes hypocalcemia (and, in CKD, there's also reduced production of calcitriol, which lowers intestinal calcium absorption). Low calcium stimulates the parathyroid glands to release more PTH, and with ongoing stimulus they undergo hyperplasia. The result is a chronically elevated PTH level driven by hypocalcemia and parathyroid gland growth, which is exactly what secondary hyperparathyroidism describes. This differs from primary hyperparathyroidism, where PTH is high despite normal or high calcium due to a glandular problem, not kidney-related phosphate and vitamin D disturbances.

In CKD, the balance of calcium and phosphate is disrupted, and that disruption drives secondary hyperparathyroidism. The failing kidneys can’t excrete phosphate effectively, so phosphate builds up in the blood. High phosphate promotes hypocalcemia (and, in CKD, there's also reduced production of calcitriol, which lowers intestinal calcium absorption). Low calcium stimulates the parathyroid glands to release more PTH, and with ongoing stimulus they undergo hyperplasia. The result is a chronically elevated PTH level driven by hypocalcemia and parathyroid gland growth, which is exactly what secondary hyperparathyroidism describes. This differs from primary hyperparathyroidism, where PTH is high despite normal or high calcium due to a glandular problem, not kidney-related phosphate and vitamin D disturbances.