In primary hyperparathyroidism, what is the typical vitamin D status?

In primary hyperparathyroidism, what is the typical vitamin D status?

• A. Normal
• B. Low
• C. Not specified
• D. High

Answer: (D)

When parathyroid hormone is elevated, it drives the kidney to make more of the active vitamin D form. PTH stimulates 1-alpha hydroxylase in the proximal tubule, increasing conversion of 25(OH)D to 1,25(OH)2D. This raises the circulating levels of active vitamin D, which enhances intestinal calcium absorption and contributes to hypercalcemia in primary hyperparathyroidism. It’s common for the 25(OH)D level (the usual measure of vitamin D stores) to be normal or even low, but the active form is typically elevated, so the overall vitamin D status is high in terms of active vitamin D.

When parathyroid hormone is elevated, it drives the kidney to make more of the active vitamin D form. PTH stimulates 1-alpha hydroxylase in the proximal tubule, increasing conversion of 25(OH)D to 1,25(OH)2D. This raises the circulating levels of active vitamin D, which enhances intestinal calcium absorption and contributes to hypercalcemia in primary hyperparathyroidism. It’s common for the 25(OH)D level (the usual measure of vitamin D stores) to be normal or even low, but the active form is typically elevated, so the overall vitamin D status is high in terms of active vitamin D.