American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the primary step in managing secondary hyperparathyroidism?

1. Increase dietary calcium

2. Correct 25-hydroxy vitamin D deficiency

3. Administer calcitriol

4. Monitor PTH levels

The correct answer is: Correct 25-hydroxy vitamin D deficiency

The primary step in managing secondary hyperparathyroidism involves correcting 25-hydroxy vitamin D deficiency. This is crucial because inadequate levels of vitamin D can lead to decreased intestinal absorption of calcium, which stimulates the parathyroid glands to produce more parathyroid hormone (PTH). By addressing the deficiency, you can help normalize calcium levels, thereby reducing the drive for excess PTH secretion. In patients with secondary hyperparathyroidism, particularly those with chronic kidney disease or malabsorption syndromes, vitamin D plays a vital role in calcium homeostasis. When sufficient vitamin D is provided, it enhances calcium absorption from the diet and can help mitigate the compensatory overactivity of the parathyroid glands. Increasing dietary calcium alone may not suffice if vitamin D levels are low, as adequate vitamin D is necessary for the body to effectively utilize calcium. Administering calcitriol (the active form of vitamin D) may also be beneficial, but it is often done in conjunction with correcting vitamin D deficiency first. Monitoring PTH levels is important for tracking the disease but does not address the underlying deficiency contributing to the problem. Thus, addressing vitamin D deficiency takes precedence as it directly influences calcium metabolism and PTH secretion.