Osteoporosis: group of diseases where bone resorption exceeds deposit. Matrix remains normal, but mass declines. Affects spongy bone (spine,femur, and neck) and common fractures in vertebrae and hip. Risk factors: postmenopausal women, 30% 60-79, 70% by 80 due to estrogen lowering, genetics, lack of exercise, low calcium, smoking, etc. Treatment: traditional= calcium, vitamin D, exercise, hormone therapy(slows bone loss but doesn't revert it; increase risk of heart attacks, strokes, and breast cancer). Other Drugs: Bisphosphonates= reduces osteoclasts particularly reverse spine bone loss. Denosumb= monoclonal antibody improves bone density and lowers fracture risks. Preventing: get enough calcium early in life, limit alcohol and carbonated drinks, do weight bearing exercise to maintain bone mass.