Which outcome related to bone health is associated with PTH injections?

• A. Bone density decreases
• B. Bone density fluctuates wildly
• C. Bone density improves
• D. No change in bone density

Answer: (C)

Intermittent parathyroid hormone injections act as an anabolic stimulus for bone. PTH regulates bone remodeling, and when given in short, periodic doses, it preferentially stimulates osteoblast activity and bone formation rather than just breaking down bone. This leads to an overall increase in bone mineral density and stronger bone, lowering fracture risk.

In this mode, PTH helps build bone over time, especially in trabecular-rich areas like the spine, which is why bone density tends to improve. If PTH exposure were continuous, the balance would shift toward bone resorption, not formation, so bone density would not improve. The goal of this therapy is to create a net gain in bone mass, not a lack of change or wild fluctuations.