Osteoporosis is a disease characterized by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk.
At this time, there is no practical way to measure micro architecture. So, only bone mass can be measured and, according to a WHO study group, four diagnostic criteria can be established in women.
Normal: a value for bone mass within 1 SD of the young adult reference mean.
Low bone mass (osteopenia): a value for bone mass more than 1 SD below the young adult mean but less than 2.5 SD below this value.
Severe osteoporosis: a value for bone mass 2.5 SD or more below the young adult mean in the presence of one or more fragility fractures.
Usually bone mass is expressed as T-score, with a T-score=0 as the young adult reference mean.
|+1 < T||high bone mass|
|1 < T < +1||normal bone mass|
|-2.5 < T < -1||osteopenia|
|T < -2.5||osteoporosis|
|T < -2.5 and fractures:||severe osteoporosis|
Although osteoporosis is also a disease of men, this classification is only available for women.
Lifetime risk of fractures
The lifetime future risk of a fracture of a person at the age of 50 is for women nearly 40% and for men about 13%
|any of these||39.7%||13.1%|
Risk factors for osteoporosis:
The main tool for this part of the risk assessment is to select women for bone mass measurement. In some countries, bone mass measurement is restricted or hardly even available.