The role of homocysteine in bone

Abstract

Osteoporosis is characterized by low bone mass and deterioration of microarchitectural structure. It is a very common disease; in 2007 it was estimated that 1.9 in 1,000 men and 16.1 in 1,000 women had diagnosed osteoporosis in the Netherlands. However, the true number is expected to be 2-3 times higher, since osteoporosis often goes undetected because it causes no symptoms until a fracture occurs. Whether one develops osteoporosis is determined by multiple factors; for instance, high age, female sex, low body weight, smoking, limited physical activity and use of medication such as glucocorticoids are all risk factors. In addition, osteoporosis is highly heritable; bone mineral density (BMD), the parameter obtained by dual-energy X-ray absorptiometry (DXA) scanning to diagnose osteoporosis, has an estimated heritability of 50-85%. Recently, 56 genetic determinants have been identified that influence BMD . Fractures are the most important possible consequence of osteoporosis. They form a major health care burden. For example, in 2005, more than 2 million fractures were reported in the United States only, leading to 17 billion dollars of costs [7]. Moreover, fractures lead to morbidity and mortality. In the Netherlands, a striking 25% of persons who sustained a hip fracture dies within one year [8]. The problem of osteoporosis and fractures is expected to increase over time because of global demographic changes due to improved health; the number of people aged ≥65 years is expected to increase from 506 million in 2008 to 1.3 billion in 2040 .