What Is Osteoporosis? What Causes Osteoporosis?

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Main Category: Bones / Orthopaedics
Also Included In: Menopause
Article Date: 28 Jun 2009 - 10:00 PDT

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The bones of people with osteoporosis become thin and weak. The word "osteo" comes from the Greek osteon meaning "bone", while "porosis" comes from the Greek poros meaning "hole, passage". According to Medilexicon's medical dictionary, osteoporosis is a "reduction in the quantity of bone or atrophy of skeletal tissue; an age-related disorder characterized by decreased bone mass and loss of normal skeletal microarchitecture, leading to increased susceptibility to fractures."

About 3 million people have osteoporosis in the UK, causing approximately 230,000 fractures each year, according to the National Health Service (NHS). Osteoporosis is a public health threat for an estimated 44 million people in the USA, 55% of people aged 50 or over, says the National Osteoporosis Foundation (NOF). The NOF says that 10 million people currently have osteoporosis, while 34 million are thought to have low bone mass; which places them at significantly increased risk for the condition.

As people are living longer and leading more sedentary lives, the incidence of osteoporosis is expected to continue rising. This study reports that policy makers and funding agencies do not always consider this development sufficiently in their planning.

If osteoporosis is not prevented, or if it is left untreated, it can progress without causing any pain until a bone breaks - most likely the hip bone, a bone in the spine, or the wrist. A hip fracture invariably requires hospitalization and major surgery. Hip fractures generally lead to serious walking disability and sometimes death if left untreated. Fractures of the spine or vertebrae can sometimes result in loss of height, severe back pain, and deformity.

German scientists have elucidated a molecular mechanism which regulates the equilibrium between bone formation and bone resorption. They were able to show that two different forms of a gene switch - a short isoform and a long isoform - determine this process

What are the symptoms of osteoporosis?

Osteoporosis develops very slowly over a period of many years. The condition may creep up on the patient without any obvious symptoms initially - it can take several months, and even several years to become noticeable. Early signs of osteoporosis may include:

• Joint pains
• Difficulty standing
• Difficulty sitting up straight. The stooping position often seen among elderly people is a visible sign of possible osteoporosis.

As the person's bone density or bone mass continues to go down fractures of the hip, wrist or bones in the spine become more common. Even a cough or a sneeze may fracture a rib or cause partial collapse of one of the spinal bones.

Elderly people suffer greatly if they fracture a bone, because the bone cannot repair itself properly. Bones that do not effectively repair themselves are more likely to trigger arthritis, eventually leaving the patient seriously disabled. A large percentage of elderly patients who break a bone are not able to live independently afterwards.

Although osteoporosis is not painful in itself, the condition causes bones to break more easily, and broken bones are very painful. The most common cause of chronic pain linked to osteoporosis is a spinal fracture.

What are the risk factors for osteoporosis? What diseases or conditions may be linked to osteoporosis?

A risk factor is something that increases a person's chances of developing a disease or condition. A number of factors can raise the probability of developing osteoporosis. They include:

• The patient's sex - women are twice as likely to develop osteoporosis as men. Experts say there are two reasons for this: 1. Women start life with a lower bone life than men. 2. Women live longer than men. 3. The menopause causes a sudden drop in estrogen in women which speeds up bone loss.


• Age - a person's bone mass lowers each year as he/she gets old. The falling bone mass continues until the person dies.


• Vertigo - Korean scientists found a link between people who suffer from vertigo and osteoporosis.


• HIV - people with HIV/AIDS have a significantly higher risk of developing osteoporosis, as this study found.


• Gastric cancer - many surviving gastric cancer patients might suffer from osteoporosis and be at risk of developing multiple fractures in their later life, this article explains.


• Ethnicity - people who are Caucasian, or of South Asian descent are more likely to develop osteoporosis than people of African or North/South American Indian descent. However, the risk is still significant for everybody.


• Family history - people who have a close relative - parent or sibling) who has/had osteoporosis are much more likely to develop it themselves. This is especially the case if the close relative had fractures. A study found that a gene called DARC negatively regulates bone density in mice.


• People with small frames - people who have small body frames, as well as people who are very thin tend to have a higher risk of developing osteoporosis when they get older. This is because their bone mass is lower than other people's when they start to age and bone density begins to fall.


• Smoking - people who smoke run a much higher risk of developing osteoporosis. Experts are not completely sure why.


• Estrogen exposure - women who have a late menopause, when estrogen levels drop significantly, have a lower risk of developing osteoporosis compared to women whose menopause arrives early or at an average age. Conversely, women whose menopause arrived early are at a higher risk.


• Anorexia and/or bulimia - people of both sexes who have, or have had eating disorders have a higher risk of developing osteoporosis. International Osteoporosis Foundation warns of bone damage from anorexia.


• Cardiovascular disease and possibly Alzheimer's disease link - a research project at Rice University has brought scientists to the brink of comprehending a long-standing medical mystery that may link cardiovascular disease, osteoporosis and perhaps even Alzheimer's disease.


• Some medications:
  
  
  • Corticosteroids - long term use of corticosteroids damages bones. Such drugs include prednisone, cortisone, prednisolone and dexamethasone. Patients with asthma, rheumatoid arthritis, and psoriasis may have been prescribed these medications. Doctors often monitor such patient's bone density and recommend other drugs to prevent bone loss.
  
  
  • Selective serotonin reuptake inhibitors (SSRIs) - these are types of antidepressants. They have been found to lower bone density. It is not completely clear yet whether they do cause osteoporosis; but the fact that they have an impact on bone density means patients on SSRIs may need to be aware.
  
  
  • Blood thinning medications - long term use may lower bone density.
  
  
  • Methotrexate - a drug used for cancer treatment.
  
  Some drugs used for epilepsy, diuretics, as well as some aluminum-containing antacids also cause bone loss.


• Thyroid hormone - if there is too much thyroid hormone in the person's body his/her bone mass may be affected. This could be caused by an overactive thyroid (hyperthyroidism) or overconsumption of medications for the treatment of hypothyroidism (underactive thyroid).


• Breast cancer - women who have had breast cancer may have a higher risk of developing osteoporosis after the menopause. This is especially the case if they were treated with chemotherapy or aromatase inhibitors (anastrozole and letrozole) which suppress estrogen. Tamoxifen, on the other hand, reduces fracture risk and is not an osteoporosis risk factor.


• Long-term low calcium consumption - people who have consumed too little calcium during their lives are at a significantly higher risk of developing osteoporosis.


• Some medical conditions and surgical procedures - especially those which may undermine or lower calcium absorption. They include:
  
  
  • Gastrectomy (stomach surgery)
  • Crohn's disease
  • Celiac disease
  • Vitamin D deficiency
  • Cushing's disease


• Long-term physical inactivity - people who have lead a generally sedentary lifestyle with little exercise are much more prone to developing osteoporosis one day, compared to people who had physically active childhoods, and adulthoods.


• Too much caffeine consumption - the association between high caffeine consumption and bone loss is highly suspected, but not completely proven. As caffeine is a diuretic it may increase mineral (calcium) loss. Many experts say that the phosphoric acid in sodas (fizzy drinks) may contribute to bone loss. People who drink lots of coffee and sodas should make sure they are consuming enough calcium and vitamin D. This study found that regular female cola drinkers have a higher risk of developing osteoporosis than women who don't drink cola.


• Alcoholism - this is the main cause of osteoporosis among males. Consuming too much alcohol regularly undermines bone formation and messes with our body's ability to absorb alcohol.


• Depression - people with depression tend to lose bone mass faster than other people.

How is osteoporosis diagnosed?

In most cases, the patient does not know he/she has osteoporosis until later on, when a bone is fractured. X-rays cannot measure bone density reliably - but they are good at identifying spinal fractures.

• DEXA scan - this scan measures bone density. DEXA stands for Dual Energy X-ray Absorptiometry. The DEXA scan measures bone densities and compares them to a normal range. The patient is then given a 'T' score. This score describes the person's bone density compared to the average. T scores are set out in the following way:
  
  
  • 0 or minus 1 - normal range bone density
  • Minus 1 to minus 2.5 is a lower bone density. The patient has osteopenia (not osteoporosis)
  • Below minus 2.5 - the patient has osteoporosis.
  
  
  The DEXA scan is fast, simple and accurate. It measures bone density in the most likely areas to be affected by osteoporosis - the spine, hip and wrist. It also follows changes in these bones over time.


• Dental X-rays - Researchers in the school of dentistry at the University of Manchester have created a unique way of identifying osteoporosis sufferers from ordinary dental X-rays.


• Ultrasound - an ultrasound scan can also provide a doctor with a reliable indication of bone density.


• CT (computerized tomography) - this can also provide a doctor with a reliable indication of bone density.


• Measuring calcium intake in men - a study revealed that measuring a man's daily calcium intake is an effective way of identifying prostate cancer patients with a higher than average risk of osteoporosis.

Who should have a test?

The National Osteoporosis Foundation says women should have a bone density test if they aren't taking estrogen and:

• Are aged 65 or over
• Are postmenopausal and have one or more risk factors for osteoporosis
• Have an abnormality in their spine
• Are taking medications which may raise the risk of osteoporosis
• Have Type 1 diabetes
• Have a liver disease
• Have a kidney disease
• Have a thyroid disease
• Have a family history of osteoporosis
• Have experienced early menopause

Doctors do not usually advise men to have routine osteoporosis tests because it is far less common among men.

Treatment for osteoporosis

• HRT (Hormone replacement therapy) - for women going through the menopause HRT helps prevent bone density loss, thus reducing the risk of fractures during treatment. In many cases, though, HRT is not recommended as the first osteoporosis treatment, because it can raise her risk of having a stroke, heart disease and breast cancer. It is important that the patient discuss this option with a doctor.


• Testosterone treatment - when a man has osteoporosis because of low testosterone production, testosterone treatment may be recommended. However, as with breast cancer, testosterone may accelerate the growth of prostate cancer as well as increasing the risk of prostate cancer recurrence.


• Bisphosphonates - these help prevent bone density loss and are non-hormonal drugs. The breakdown rate of bone by osteoclasts is slowed down while the production of new bone is speeded up. If biphosphonates are unsuitable strontium ranelate might be a good alternative. Taking just one pill per month may help slow down bone loss, this study revealed. Side effects may include abdominal pain, nausea, inflamed esophagus, esophageal ulcers (especially for patients who have had acid reflux) - side effects may be severe. A study revealed that short term use of oral bisphosphonates may leave the jaw vulnerable to devastating necrosis (death of bone tissue).


• Calcitonin - this inhibits the cells that break down bone. Calcitonin is a hormone made by the thyroid gland.


• Calcium and vitamin D supplements - these may help older patients lower their risk of hip fractures. Sunlight is the best source of vitamin D. If patients do not have access to sunlight, as may be the case during the winter in some countries, the doctor may recommend a supplement. A Canadian study found that less than half (43%) of patients in Europe with osteoporosis are claiming to take both calcium and vitamin D supplementation with their osteoporosis treatment.


• SERMs (Selective estrogen receptor modulators) - these drugs help prevent bone density loss. They mimic the beneficial effects of estrogen on bone density in postmenopausal women - however, without the risk of triggering cancers. Raloxifene is an example of this type of drug. Patients who have a history of blood clots should not take this medication. A common side effect is hot flashes. This drug is only approved for women with osteoporosis, not men.


• Stem cell therapy - scientists report that stem cells could halt osteoporosis, promote bone growth - and new pathways that controls bone remodeling.

Complications of osteoporosis

• Fractures in the spinal column can cause loss of height because the spine cannot bear the person's body weight, leading to the characteristic hunched posture. These fractures may occur without any fall or blow to the bones.


• Minor falls can cause fractures to the wrist, neck, forearm, and hip bones.


• Weakened bones can cause disability and loss of mobility.


• Hip replacements are frequently required after a fracture, making it extremely difficult for the person to walk without help.


• Death can result from postoperative complications, especially if the osteoporosis patient is elderly.


• Many patients with osteoporosis have to be looked after in nursing homes as a result of loss of mobility.

Prevention

• Calcium - Make sure your calcium intake is adequate. The National Osteoporosis Foundation (NOF) says adults under 50 years of age need 1,000 mg of calcium per day, while people over 50 need 1,200 mg of calcium each day.


• Vitamin D - Make sure your vitamin D intake is adequate. Remember that sunlight is a brilliant source of vitamin D. You need vitamin D for your body to be able to absorb calcium. The NOF says people under 50 require 400-800 IU of vitamin D daily, while those over 50 require 800-1,000 IU of vitamin D daily. Two types of vitamin D supplements are available - vitamin D₃ and vitamin D₂. Some research suggests that vitamin D₃ is better, while others indicate that it does not matter.


• Exercise - Make sure you are physically active. The best exercises to prevent osteoporosis are those in which you have to carry the weight of your body, such as walking, dancing, jogging, stair-climbing, racquet sports and hiking. This study reveals that cycling does not help prevent osteoporosis - in fact, the opposite may be the case.


• Soy - Eat soy and soy products. They contain plant estrogens which help maintain bone density.


• Smoking - Quit smoking.


• HRT - Consider hormone therapy (HRT). However, bear in mind the risk of cancers for some people. Talk about this with your doctor.


• Alcohol - Control your consumption of alcohol. Excessive alcohol consumption is closely linked to loss of bone mass.


• Caffeine - Do not consume too much caffeine. Remember that many sodas (fizzy drinks) also contain caffeine.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today