Now we know that it is really a disease of young women, even young girls. Study of bone metabolism, improved diagnostic tests, new therapeutic options - all these changed the old notions and hopefully will lead to improved prevention and treatment of this potentially deadly condition. Their relative risk is arbitrarily set at 1. As BMD decreases the risk of fracture goes up.
Standard deviation is a mathematical tool used in statistical calculations.
Patients whose BMD is 1 SD lower than that of young healthy women have double the risk of fracture. If it's 2 SD lower, the risk increases to 4. Osteoporosis - more than 2.5 SD below peak bone mass. Most physicians feel that a woman should not wait until her bones lose enough mass to be 2.5 SD below and treatment should begin somewhere around 2 SD or earlier. Bone mass Bone mass increases from childhood to about the age 35, where it peaks and gradually begins to diminish, causing bones to become less dense.