Bones, which comprise the greater part of the skeletal system, are generally in a state of constant renewal. This renewal happens through the processes of modeling when the bone is formed at one site and broken in another, and remodeling when the bone tissue is broken and formed again in the same site. Remodeling of the bone tissue constitutes a normal physiological process that occurs constantly. There are two types of cells responsible for it: osteoclasts for bone resorption and osteoclasts for subsequent bone formation. Typically, the rate of bone resorption is regulated through interaction between the protein called receptor activator of nuclear factor kappa B ligand (RANKL), osteoclast precursors (RANK), and osteoprotegerin (OPG) – a protein that may prevent RANKL/RANK interaction and creation of new osteoclasts. However, inactive lifestyle, nutrition deficiencies, the varying levels of certain hormones, and the loss of ability to replenish bone cells with age may cause increased resorption and the loss of bone mass. This loss, in turn, leads to several medical conditions, including osteoporosis.
Among the causal factors of osteoporosis listed above, many may be addressed through appropriate treatment. The decrease in bone cell replenishment with age is irreversible, but one may correct nutritional deficiencies through a well-thought diet. Physical activity at a younger age helps the development of a stronger skeleton. Estrogen replacement also helps to address osteoporosis in women by revising negative calcium balance. Therefore, hormonal replacement therapy addresses some of the causal factors of osteoporosis, but is not a universal solution, as it does not substitute for proper nutrition and physical activity.
Osteoporosis occurs due to a malfunctioning of the skeletal system and other connected systems. Normally, bone resorption and formation by osteoclasts and osteoblasts balance each other through the interaction of RANK, RANKL, and OPG. If this interaction is flawed due to carrying levels of certain hormones and nutritional deficiencies, this may, especially when combined with an inactive lifestyle and the loss of ability to replenish bone cells with age, lead to osteoporosis. Hormone replacement is one of the ways to address negative calcium balance, but neither the only one nor a universal solution.