Osteoporosis: Definition, causes, diagnosis and prevention

Definition

Osteoporosis is a condition characterized by a decrease in the density of bone, decreasing its strength and resulting in fragile bones. Osteoporosis literally leads to abnormally porous bone that is compressible, like a sponge. This disorder of the skeleton weakens the bone and results in frequent fractures (breaks) in the bones.

Normal bone is composed of protein, collagen, and calcium, all of which give bone its strength. Bones that are affected by osteoporosis can break (fracture) with relatively minor injury that normally would not cause a bone to fracture. The fracture can be either in the form of cracking (as in a hip fracture) or collapsing (as in a compression fracture of the vertebrae of the spine). The spine, hips, ribs, and wrists are common areas of bone fractures from osteoporosis although osteoporosis-related fractures can occur in almost any skeletal bone.

Primary and Secondary osteoporosis

  • Primary osteoporosis is the most common type of osteoporosis. It can be age-related and associated with the postmenopausal decline in estrogen levels, or related to calcium and vitamin D insufficiency.
  • Secondary osteoporosis is osteoporosis caused by other conditions, such as hormonal imbalances, diseases, or medications (such as corticosteroids or anti-seizure drugs).

History about osteoporosis

The link between age-related reductions in bone density and fracture risk goes back at least to Astley Cooper, and the term “osteoporosis” and recognition of its pathological appearance is generally attributed to the French pathologist Jean Lobstein. The American endocrinologist Fuller Albright linked osteoporosis with the postmenopausal state. Bisphosphonates were discovered in the 1960s. Anthropologists have studied skeletal remains that showed loss of bone density and associated structural changes that were linked to a chronic malnutrition in the agricultural area in which these individuals lived. “It follows that the skeletal deformation may be attributed to their heavy labor in agriculture as well as to their chronic malnutrition”, causing the osteoporosis seen when radiographs of the remains were made.

Prevalence of osteoporosis

Due to its prevalence worldwide, osteoporosis is considered a serious public health concern. Currently it is estimated that over 200 million people worldwide suffer from this disease. Approximately 30% of all postmenopausal women have osteoporosis in the United States and in Europe. At least 40% of these women and 15-30% of men will sustain one or more fragility fractures in their remaining lifetime. Ageing of populations worldwide will be responsible for a major increase in the incidence of osteoporosis in postmenopausal women.

It has been shown that an initial fracture is a major risk factor for a new fracture. An increased risk of 86% for any fracture has been demonstrated in people that have already sustained a fracture5. Likewise, patients with a history of vertebral fracture have a 2.3-fold increased risk of future hip fracture and a 1.4-fold increase in risk of distal forearm fracture

Risk factors and causes that make osteoporosis more likely includes

  • Age –Your bone density peaks around age 30. After that, you’ll begin to lose bone mass.
  • Gender – Women over the age of 50 are the most likely people to develop osteoporosis.
  • Family history – If your parents or grandparents have had any signs of osteoporosis, such as a fractured hip after a minor fall, you may be more likely to get it, too.
  • Bone structure and body weight – Petite and thin women have a greater chance of developing osteoporosis.
  • Broken bones – If you’ve had fractures before, your bones may not be as strong.
  • Ethnicity – Research shows that Caucasian and Asian women are more likely to develop osteoporosis than women of other ethnic backgrounds.
  • Certain diseases – Some diseases such as rheumatoid arthritis raise the odds that you’ll get osteoporosis.
  • Some medications – Certain prescription medications for example, if you take steroids such as prednisone for a long time can also boost your odds of getting osteoporosis.
  • Smoking – It’s bad for your bones.
  • Alcohol – Heavy drinking can lead to thinning of the bones and make fractures more likely.
  • Hyperthyroidism – a condition wherein too much thyroid hormone is produced by the thyroid gland (as in Grave’s disease) or is ingested as thyroid hormone medication
  • Inherited disorders of connective tissue, including osteogenesis imperfecta, homocystinuria, osteoporosis-pseudoglioma syndrome and skin diseases, such as Marfan syndrome and Ehlers-Danlos syndrome
  • Vitamin D deficiency.
  • Amenorrhea (loss of the menstrual period) in young women is associated with low estrogen and osteoporosis; amenorrhea can occur in women who undergo extremely vigorous exercise training and in women with very low body fat (for example, women with anorexia nervosa).

Symptoms of Osteoporosis

There typically are no symptoms in the early stages of bone loss. But once your bones have been weakened by osteoporosis, you may have signs and symptoms that include:

  • Back pain, caused by a fractured or collapsed vertebra
  • Loss of height over time
  • A stooped posture
  • A bone fracture that occurs much more easily than expected
  • Difficulty getting up from a chair without using your arms to push
  • Joint or muscle aches

Complications

Bone fractures, particularly in the spine or hip, are the most serious complication of osteoporosis. Hip fractures often are caused by a fall and can result in disability and even an increased risk of death within the first year after the injury.

Compression at the spine

In some cases, spinal fractures can occur even if you haven’t fallen. The bones that make up your spine (vertebrae) can weaken to the point that they may crumple, which can result in back pain, lost height and a hunched forward posture.

Diagnosis of osteoporosis

  • Bone density scan – This exam is used to measure bone mineral density (BMD). It is most commonly performed using dual-energy x-ray absorptiometry (DXA or DEXA) or bone densitometry. The amount of x-rays absorbed by tissues and bone is measured by the DXA machine and correlates with bone mineral density.
  • Bone x-ray – Bone x-ray aids in the diagnosis of fractured bones, which are sometimes a result of osteoporosis.
  • CT scan of the spine – CT scanning of the spine is performed to assess for alignment and fractures. It can be used to subjectively measure bone density and determine whether vertebral fractures are likely to occur. This technique is called quantitative CT (QCT).
  • MRI of the spine – Magnetic resonance imaging of the spine is performed to evaluate vertebral fractures for evidence of underlying disease, such as cancer, and to assess the newness of the fracture. New fractures demonstrate a better response to treatment by vertebroplasty and kyphoplasty in certain clinical situations.
  • Ultrasound – which typically tests the heel of your foot, can also detect early signs of osteoporosis.
  • In addition to these bone density tests, your doctor might take blood or urine samples and test them to see if you have another disease that’s causing bone loss.

Treatment and Medications for Osteoporosis

For both men and women at increased risk of fracture, the most widely prescribed osteoporosis medications are bisphosphonates. Examples include:

  • Alendronate (Fosamax)
  • Risedronate (Actonel, Atelvia)
  • Ibandronate (Boniva)
  • Zoledronic acid (Reclast)

Hormone-related therapy: Raloxifene (Evista) mimics estrogen’s beneficial effects on bone density in postmenopausal women, without some of the risks associated with estrogen.

Denosumab (Prolia): Compared with bisphosphonates, denosumab produces similar or better bone density results and reduces the chance of all types of fractures. Denosumab is delivered via a shot under the skin every six months.

Teriparatide (Forteo): This powerful drug is similar to parathyroid hormone and stimulates new bone growth. It’s given by daily injection under the skin. After two years of treatment with teriparatide, another osteoporosis drug is taken to maintain the new bone growth.

Prevention of osteoporosis

  • Regular exercise is essential.
  • Weight-bearing exercises are exercises where your feet and legs support your weight. High-impact weight-bearing exercises, such as running, skipping, dancing, aerobics, and even jumping up and down on the spot
  • Resistance exercises use muscle strength, where the action of the tendons pulling on the bones boosts bone strength. Examples include press-ups, weightlifting or using weight equipment at a gym. Calcium is important for maintaining strong bones. Calcium-rich foods include:
  • Leafy green vegetables
  • Dried fruit
  • Tofu
  • Yoghurt
  • Vitamin D is also important for healthy bones and teeth because it helps your body absorb calcium. Good dietary sources are:
  • Oily fish – such as salmon, sardines, herring and mackerel
  • Red meat
  • Liver
  • Egg yolks
  • Fortified foods such as most fat spreads and some breakfast cereals
  • Dietary supplements.

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