There are two types of bone: trabecular and cortical. Trabecular bone is primarily found in the spine, skull, pelvis, and in the ultra-distal radius, while cortical bone predominates in the long bones, the femoral neck and distal radius. Trabecular bone metabolizes more, making it more susceptible to changes in bone mass.During childhood bone formation exceeds reabsorption and remodeling is intense. There are two periods during which growth is accelerated: during the first two years of life and during adolescence (between 11 and 14 years for girls and 13 and 17 years for boys).Factors that interfere with bone formation can be divided into two groups: intrinsic and extrinsic factors. The former include hereditary factors (responsible for around 80% of final peak bone mass), race, sex and hormonal factors (growth hormone, insulin-dependant growth factor I, estrogen and testosterone), while extrinsic factors are related to nutritional elements, mechanical factors, habits, the existence of chronic diseases and the use of medications.