In vitamin D deficiency, which parameter may be elevated?

In vitamin D deficiency, which parameter may be elevated?

• A. Calcitonin
• B. GH
• C. iPTH
• D. TSH

Answer: (C)

When vitamin D is deficient, calcium absorption from the gut drops, which can lower serum calcium. The body responds by increasing intact parathyroid hormone to restore calcium levels, a situation known as secondary hyperparathyroidism. PTH raises calcium by promoting bone resorption, increasing renal calcium reabsorption, and stimulating production of active vitamin D in the kidney (to whatever extent substrate is available). This makes the elevated parameter the parathyroid hormone level. The other hormones listed don’t have a primary role in this calcium-balancing response: calcitonin is usually tied to high calcium, while GH and TSH are not direct regulators of calcium homeostasis in this context.

When vitamin D is deficient, calcium absorption from the gut drops, which can lower serum calcium. The body responds by increasing intact parathyroid hormone to restore calcium levels, a situation known as secondary hyperparathyroidism. PTH raises calcium by promoting bone resorption, increasing renal calcium reabsorption, and stimulating production of active vitamin D in the kidney (to whatever extent substrate is available). This makes the elevated parameter the parathyroid hormone level. The other hormones listed don’t have a primary role in this calcium-balancing response: calcitonin is usually tied to high calcium, while GH and TSH are not direct regulators of calcium homeostasis in this context.