Osteoporosis

Osteoporosis is a disease of bone in which the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. Osteoporotic bones are more at risk of fracture. Osteoporosis is defined by the World Health Organization (WHO) in women as a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by DXA; the term "established osteoporosis" includes the presence of a fragility fracture. While treatment modalities are becoming available (such as the bisphosphonates), prevention is still considered the most important way to reduce fracture. Due to its hormonal component, more women, particularly after menopause, suffer from osteoporosis than men. In addition it may be caused by various hormonal conditions, smoking and medications (specifically glucocorticoids) as well as many chronic diseases.
Risk factors

Risk factors for osteoporotic fracture can be split between modifiable and non-modifiable:

* Nonmodifiable: history of fracture as an adult, family history of fracture, female sex, advanced age, European or Asian ancestry, and dementia
* Potentially modifiable: prolonged intake of the prescription drug prednisone or any other glucocortioid, tobacco smoking, low body mass index, estrogen deficiency, early menopause (<45 years) or bilateral oophorectomy, premature ovarian failure, prolonged premenopausal amenorrhea (>1 year), low calcium and vitamin D intake, alcoholism, impaired eyesight despite adequate correction, high risk of falls or recurrent falls, inappropriate physical activity (i.e. too little or also if done in excess), poor health/frailty. Coeliac disease can lead those with an otherwise adequate calcium intake to develop osteoperosis due to the inability to absorb calcium. Osteoporotic fracture may indeed be the event that leads to diagnosis that coeliac disease (which affects around one in a hundred people in the West) has affected the patient for many years. The effects of soft drinks (containing phosphoric acid) are debatable; soft drinks may merely displace calcium-containing drinks from the diet.

A strong association between cadmium, lead and bone disease has also been established. Low level exposure to cadmium is associated with an increased loss of bone mineral density readily in both genders, leading to pain and increased risk of fractures, especially in elderly and in females. Higher cadmium exposure results in osteomalacia (softening of the bone).[1][2][3] An association with proton pump inhibitors has also been found: it is thought that reducing the level of stomach acid interferes with calcium absorption.[4]

[edit] Etiology

Family history of fracture or low bone mass are probably the most important etiological factors of primary osteoporosis. The heritability of the fracture as well as low BMD are relatively high, ranging from 25 to 80 percent. Estrogen deficiency following menopause is correlated with a rapid reduction in BMD. This, plus the increased risk of falling associated with aging, leads to fractures of the wrist, spine and hip. Other hormone deficiency states can lead to osteoporosis, such as testosterone deficiency. Glucocorticoid or thyroxine excess states also lead to osteoporosis. Lastly, calcium and/or vitamin D deficiency from malnutrition increases the risk of osteoporosis.

Other significant factors leading to the onset of osteoporosis include smoking cigarettes, low levels of physical activity (weight bearing exercise), and family history. Osteoporosis can be thought of as analogous to sarcopenia, which is the age-related loss of skeletal muscle. The combination of sarcopenia and osteoporosis results in the significant frailty often seen in the elderly population.

List of disorders associated with osteoporosis:

* Hypogonadal states - Turner syndrome, Klinefelter syndrome, Kallmann syndrome, anorexia nervosa, hypothalamic amenorrhea, hyperprolactinemia
* Other endocrine disorders - Cushing's syndrome, hyperparathyroidism, thyrotoxicosis, hypothyroidism, insulin-dependent diabetes mellitus, acromegaly, adrenal insufficiency
* Nutritional and gastrointestinal disorders - malnutrition, parenteral nutrition, malabsorption syndromes (e.g. coeliac disease, Crohn's disease), gastrectomy, severe liver disease (especially primary biliary cirrhosis)
* Rheumatologic disorders - rheumatoid arthritis, ankylosing spondylitis
* Hematologic disorders/malignancy - multiple myeloma, lymphoma and leukemia, mastocytosis, hemophilia, thalassemia.
* Inherited disorders - osteogenesis imperfecta, Marfan syndrome, hemochromatosis, hypophosphatasia, glycogen storage diseases, homocystinuria, Ehlers-Danlos syndrome, porphyria, Menkes' syndrome, epidermolysis bullosa, Gaucher's disease.
* Medication:
o Steroid-induced osteoporosis (SIOP) due to use of glucocorticoids - analogous to Cushing's syndrome and involving mainly the axial skeleton
o Barbiturates (due to accelerated metabolism of vitamin D) and some other antiepileptics
* Other disorders - immobilization, scoliosis
source:en.wikipedia.org