Osteoporosis is a disease of the bones that makes them weak and prone to fracture.
Osteoporosis is considered a silent disease, because bone loss itself is gradual and painless. There are usually no symptoms to indicate that a person is developing osteoporosis early in the condition. Bone is living tissue that is in a constant state of formation and resorption. Bone resorption is the gradual loss of bone. As individuals age, formation lessens and after a peak bone mass is achieved, bone mass remains stable (resorption and formation are equal). Osteoclasts are the principal cells responsible for bone resorption.
By their mid-30s, most individuals begin to gradually lose bone strength as the balance between bone resorption and bone formation shifts, so that more bone is lost than can be replaced. As a result, bones become less dense and structurally weaker, called osteopenia. Osteopenia refers to mild bone loss that is not severe enough to be called osteoporosis, but that increases the risk of developing osteoporosis. As this occurs, bones lose calcium, phosphorus, boron, and other minerals and become lighter, less dense, and more porous. This makes the bones weaker and increases the chance that they might break. If not prevented or if left untreated, osteopenia can progress painlessly into osteoporosis until a bone breaks or fractures.
Although any bone is susceptible to fracture, the most common fractures in osteoporosis occur at the spine, wrist, and hip. Spine and hip fractures in particular may lead to chronic pain, long-term disability, and even death.
Osteoporosis is more common in older individuals and non-Hispanic white women, but can occur at any age, in men as well as in women, and in all ethnic groups.
According to the National Osteoporosis Foundation, about eight million women and two million men in the United States have osteoporosis. Those over the age of 50 are at greatest risk of developing osteoporosis and suffering related fractures. In this age group, one in two women and one in six men will suffer an osteoporosis-related fracture at some point in their life.
Significant risk has been reported in people of all ethnic backgrounds. While osteoporosis is often thought of as an condition found in older individuals, it can strike at any age.
Osteoporosis may also affect children, although it is rare. This is called juvenile osteoporosis. Juvenile osteoporosis is usually due to a medical condition, such as a thyroid condition or Cushing's disease (a rare condition involving insufficient adrenal hormone output), or medications, including corticosteroids. It's a significant problem because it occurs during the child's prime bone-building years.
Conditions that may cause bone loss include osteomalacia, osteochondrosis, Kashin-Beck disease, and skeletal fluorosis. Osteomalacia is a softening of the bones, resulting from defective bone mineralization. Osteomalacia may cause pain, weakness, and fragility of the bones. Osteomalacia is caused by insufficient nutritional quantities or faulty metabolism of vitamin D or calcium, following a parathyroidectomy (removal of the parathyroid gland), or in other conditions such as cystic fibrosis, renal osteodystrophy (failure of kidneys to maintain adequate blood nutrients for bone), and hepatic osteodystrophy (failure of the liver to produce adequate vitamin D).
Kashin-Beck disease is a disorder of the bones and joints of the hands, fingers, elbows, knees, and ankles of children and adolescents who slowly develop stiff deformed joints, shortened limb length, and short stature due to necrosis (death) of the growth plates of bones and of joint cartilage.
Osteochondrosis is a disease that affects the progress of bone growth by killing bone tissue. Osteochondrosis is seen only in children and teens whose bones are still growing. Osteochondrosis is an inherited condition. Individuals with osteochondrosis nearly all have pain in the location of the bone damage. Some may involve considerable swelling, limping, bending, or kyphosis (exaggerated curve) of the upper spine.
Skeletal fluorosis is the chronic intake of excessive fluoride. Skeletal fluorosis can lead to severe and permanent bone and joint deformations. This can lead to softening of the bone and increases in fractures. Skeletal fluorosis should not occur with fluorinated water or toothpaste use.

Related Terms

Alcoholism, ankylosing spondylitis, anorexia nervosa, anticonvulsant-induced osteomalacia, BMD, bone mineral density, bulimia, cartilage, corticosteroid, Crohn's disease, Cushing's disease, cystic fibrosis, dal photon absorptiometry, DEXA, diuretics, DPA, dual-energy X-ray absorptiometry, eating disorders, estrogen, fracture, gastrectomy, hepatic osteodystrophy, hormonal replacement therapy, HRT, hyperparathyroidism, hyperthyroidism, hysterectomy, I.U., International unit, juvenile osteoporosis, Kashin-Beck disease, kyphoplasty, kyphosis, menopause, oophrectomy, osteochondrosis, osteomalacia, osteopenia, osteopenic, osteoporotic, parathyroidectomy, P-DEXA, peak bone loss, peripheral dual-energy X-ray absorptiometry, postmenopausal, progestin, QCT, quantitative computer tomography, renal osteodystrophy, selective estrogen receptor modulators, SERMS, skeletal fluorosis, single-energy X-ray absorptiometry, smoking, smoking cessation, SXA, testosterone, ultrasound, vertebroplasty.