Bone grows from birth through puberty to reach its maximum around the age of thirty five. This phase in life when we have the best possible bone strength is termed the peak bone mass. Bone mass then begins to decline due to the imbalance of formation and resorption. This loss is particularly rapid in women in the first 10 years after menopause because of the lack of female sex hormone, oestrogen. Osteoporosis therefore is the end result of an inadequate attainment of peak bone mass, or a subsequent rapid loss, or a combination of both.
Evidence suggests that there is a strong genetic influence on peak bone mass.
The level of peak bone mass is also modified by environmental factors like hormones, nutrition and exercise. The environmental influences on bone are well known. The use of certain medications like heparin and corticosteroids are also known to cause rapid bone loss. Lack of these sex hormones for instance in delayed puberty, prolonged absence of menstrual periods or early menopause can influence bone mass adversely. Let us now consider the genetic influence on bone strength.