In secondary hyperparathyroidism, the rise in PTH is primarily a response to which condition?

In secondary hyperparathyroidism, the rise in PTH is primarily a response to which condition?

• A. Hypocalcemia
• B. Hypercalcemia
• C. Hyperphosphatemia
• D. Hypophosphatemia

Answer: (A)

PTH release is driven by low serum calcium detected by calcium-sensing receptors on the parathyroid glands. In secondary hyperparathyroidism, the underlying problem (often chronic kidney disease) leads to conditions that lower calcium—linking phosphate retention and reduced production of active vitamin D, which decreases intestinal calcium absorption. The fall in calcium is the primary trigger for the parathyroids to secrete more PTH in an attempt to restore calcium levels. Hypercalcemia would suppress PTH, while hypophosphatemia isn’t the stimulus for this condition. So the rise in PTH mainly reflects a response to low calcium.

PTH release is driven by low serum calcium detected by calcium-sensing receptors on the parathyroid glands. In secondary hyperparathyroidism, the underlying problem (often chronic kidney disease) leads to conditions that lower calcium—linking phosphate retention and reduced production of active vitamin D, which decreases intestinal calcium absorption. The fall in calcium is the primary trigger for the parathyroids to secrete more PTH in an attempt to restore calcium levels. Hypercalcemia would suppress PTH, while hypophosphatemia isn’t the stimulus for this condition. So the rise in PTH mainly reflects a response to low calcium.