Peak bone density

Bone mass increases rapidly during childhood and adolescence to 90% of adult levels. It reaches a peak in the third decade (the peak bone mass or peak bone density), then plateaus and finally starts to decrease (1).

• in women, bone density remains stable for the next 10-15 years after the peak bone mass
• bone loss in the hip usually starts premenopausally, usually in the fourth or fifth decade
• spinal bone loss before the menopause is less well established.
• in men, bone loss probably starts in the fifth decade.

Genetic factors account for 80% of the peak bone mass.

Environmental factors include:

• smoking - reduces peak bone mass
• weight-bearing exercise - increases peak bone mass
• high calcium intake - may increase peak bone mass

Reference:

• (1) Gafni RI, Baron J. Childhood bone mass acquisition and peak bone mass may not be important determinants of bone mass in late adulthood. Pediatrics. 2007;119 Suppl 2:S131-6