INBDE Practice Exam 2026 – Complete Study Guide

Osteopetrosis, also known as "marble bone disease," is a rare inherited disorder that causes increased bone density, anemia, deafness, blindness, and bone fractures. This is caused by a defect in the bone cells, leading to overgrowth and brittleness of the bones. Osteoporosis (choice A) is a more common condition where bone mass decreases, leading to weaker bones and a higher risk of fractures. Osteopenia (choice B) is the early stage of osteoporosis, where bone density is lower than normal, but not as severe as osteoporosis. Osteomalacia (choice C) is a condition where the bones become soft and weak due to problems with calcium absorption. It is not associated with increased bone density.