What is a risk factor for developing osteoporosis?

Increased parathyroid hormone (PTH) is a risk factor for osteoporosis. PTH stimulates osteoclast activity, promoting bone resorption and the release of calcium from bone tissue into the bloodstream. When PTH is chronically elevated, as occurs in hyperparathyroidism, the net effect is progressive loss of bone mineral density, increasing the risk of osteoporosis and fractures. Increased daily exercise, particularly weight-bearing and resistance exercise, is actually protective against osteoporosis because mechanical loading stimulates osteoblast activity and promotes bone formation, making this option incorrect. Increased dietary protein in moderate amounts supports bone health by enhancing calcium absorption and providing the building blocks for bone matrix; it is not a recognized risk factor. Increased dietary intake of vitamin D is also protective, not a risk factor, because vitamin D is essential for intestinal calcium absorption and bone mineralization. Its deficiency is associated with osteoporosis. Therefore, among the options, only elevated PTH promotes bone loss through osteoclast stimulation, making it the correct risk factor for osteoporosis development. Students often confuse the effects of PTH on bone with the beneficial effects of calcium and vitamin D supplementation, which work in the opposite direction to preserve bone mass.