Which statement best describes osteitis fibrosa cystica?

Which statement best describes osteitis fibrosa cystica?

• A. It is a bone disease with high turnover and elevated alkaline phosphatase
• B. It is a bone disease with low turnover and low alkaline phosphatase
• C. It is a disease with increased bone density
• D. It is not associated with hyperparathyroidism

Answer: (A)

Osteitis fibrosa cystica is the skeletal manifestation of excessive parathyroid hormone activity, so it represents a high-turnover bone disease. PTH ramps up bone resorption by osteoclasts and, in response, osteoblasts try to keep up, leading to rapid bone remodeling with fibrous tissue replacement and cystic, brown-tumor–like changes. Because this process involves active osteoblastic activity to form new bone, the marker of bone formation—alkaline phosphatase—is elevated. This combination—high bone turnover with an elevated alkaline phosphatase—best fits the condition. A low-turnover scenario wouldn’t reflect the PTH-driven remodeling, increased bone density isn’t characteristic, and the disease is classically linked to hyperparathyroidism, not independent of it.

Osteitis fibrosa cystica is the skeletal manifestation of excessive parathyroid hormone activity, so it represents a high-turnover bone disease. PTH ramps up bone resorption by osteoclasts and, in response, osteoblasts try to keep up, leading to rapid bone remodeling with fibrous tissue replacement and cystic, brown-tumor–like changes. Because this process involves active osteoblastic activity to form new bone, the marker of bone formation—alkaline phosphatase—is elevated. This combination—high bone turnover with an elevated alkaline phosphatase—best fits the condition. A low-turnover scenario wouldn’t reflect the PTH-driven remodeling, increased bone density isn’t characteristic, and the disease is classically linked to hyperparathyroidism, not independent of it.