Osteoporosis or porous bones affects 10 million Americans and an additional 34 million have low bone density and are at risk for the disease. Osteoporosis is the condition where bones become so weak and brittle that sometimes even normal activities can cause a fracture. Osteoporosis can lead to hip fractures and physical decline, and is a major cause of nursing-home admissions among the elderly. The disorder is more prevalent in women.
After bone mass peaks around age 35 all adults start to lose bone. Women tend to suffer from bone loss more than men do. This is in part due to having smaller, lighter bones than men. Menopause also plays its part in speeding bone loss. Bones tend to be depleted of calcium owing to the lack of estrogen. Estrogen is the female sex hormone that, among other functions, protects against bone loss. Researchers at the Indiana University School of Medicine in Indianapolis found that a drop in estrogen leads to an overproduction of bone-scavenger cells, which carve pits and craters throughout the skeleton. Estrogen helps inhibit a chemical interleukin-6, which helps keep bone destruction and bone formation in balance. Osteoblasts or bone-formation cells usually manage to fill these pits with new bone. But in the reduction of estrogen production the balance between osteoclasts and osteoblasts is disturbed.
It has also been shown that women who are nursing tend to lose bone mass although this is gained back within 6 months after weaning.
The following are considered the leading causes of bone loss