What is the role of vitamin D in osteoporosis management, and what is the target serum level?

• A. Vitamin D inhibits calcium absorption; target 10 ng/mL
• B. Vitamin D promotes calcium absorption and bone mineralization; target 25‑OH vitamin D > 30 ng/mL
• C. Vitamin D reduces bone mineralization; target 50 ng/mL
• D. Vitamin D is only important for immune function; target irrelevant

Answer: (B)

Vitamin D’s main role in osteoporosis management is to promote calcium absorption from the gut and support bone mineralization. When vitamin D levels are adequate, calcium from the diet is absorbed more efficiently, making it available for bone formation and maintenance. This helps strengthen bone and works alongside osteoporosis medications to reduce fracture risk. The commonly targeted level is a serum 25-hydroxyvitamin D above 30 ng/mL, with many guidelines aiming for roughly 30–50 ng/mL to optimize bone health. Levels that are too low (such as 10 ng/mL) indicate deficiency and compromise bone health, while aiming for 50 ng/mL is not necessary for all patients and isn’t the standard target. Statements claiming vitamin D inhibits calcium absorption, reduces bone mineralization, or is only important for immune function are not accurate.