Osteoporosis is of particular interest to postmenopausal women, but the bone condition also affects other groups of people.
Contents of this article:
What is osteoporosis?
The origin of the word 'osteoporosis' begins to explain the condition - 'osteo' is for bones, and 'porosis' means porous, resulting in weakness.1
For people who have osteoporosis, there is a higher risk of breaking a bone during a fall.2
Osteoporosis is a bone condition that makes bones thinner and more fragile because of reduced bone density, and it puts people at risk of fractures, especially of the hip, spinal vertebrae and wrist.3,4
Osteoporosis results in a loss of bone mineral density and a higher risk of fractures.
Both men and women are affected, but women more commonly, and in the US, over 40 million people have osteoporosis or are at high risk because of low bone mass, according to the National Institutes of Health.3
During their lifetime, half of all postmenopausal women will have an osteoporosis-related fracture, says the US Preventive Services Task Force.5
One estimate puts the financial cost of osteoporosis across 27 European countries at 37 billion euros in 2010, in terms of the cost of bone fractures. The researchers cite that, around the world, an estimated 1,000 fractures happen every hour because of osteoporosis.6
Fast facts on osteoporosis
Here are some key points about osteoporosis. More detail and supporting information is in the body of this article.
- Osteoporosis is a bone disease affecting the bone structure and strength and raising the risk of fractures.
- Postmenopausal women are most likely to get the condition, but it also affects men and younger people.
- There are risk factors for osteoporosis, including avoidable causes such as smoking.
- There are no symptoms caused by the loss of bone density in osteoporosis.
- Fractures are most likely in the spine, hip and wrists.
- Diagnosis is made directly via a special X-ray-based scan, but sometimes ultrasound.
- Treatments include drugs that prevent or slow down bone loss, exercise programs, and dietary adjustments, including extra calcium and vitamin D.
- Taking measures to avoid falls is important in the prevention of fractures in people who have osteoporosis.
What causes osteoporosis?
A number of risk factors have been identified that raise the likelihood of getting osteoporosis - some of these are modifiable (something you can do something about) while others cannot be avoided.
Non-modifiable risk factors for osteoporosis include:2,7,8
- Age - risk increases with age after the mid-30s
- Being Caucasian or Asian
- Small bone structure
- Osteoporosis in the family (a parent or sibling having the disease, but particularly a parent having a hip fracture)
- Previous fracture during a low-level injury, at age over 50 years in particular.
The density of bone, and the integrity of its honeycomb structure, are maintained as turnover occurs when old bone is replaced by new.9 Bone density reduces for everyone after the peak that is reached in the late twenties, so that as we get older after 35 years of age, our bones naturally become gradually weaker, but leading to osteoporosis and fractures in some people.7
Risk factors for osteoporosis that can be modified include:2,7,8
- Reduced sex hormones, particularly in women (less estrogen after the menopause, for example)
- Anorexia nervosa and bulimia (eating disorders)
- Tobacco smoking
- Excessive alcohol intake
- Reduced calcium and vitamin D (low dietary intake or inadequate gut absorption/malabsorption)
- Inactivity or immobility (stress and weight-bearing are needed for bone growth).
Other factors that increase the risk of osteoporosis are diseases or drugs that cause changes in hormone levels, and drugs that reduce bone mass.2,7 Hormone-changing diseases include hyperthyroidism, hyperparathyroidism and Cushing's disease. Rheumatoid arthritis and ankylosing spondylitis also increase osteoporosis risk.2
Medications that create a risk of osteoporosis include:2
- Glucocorticoids/corticosteroids, including prednisone (Deltasone, Orasone, for example) and prednisolone (Prelone)
- Excess thyroid hormone replacement
- Heparin, the blood-thinner
- Anastrozole (Arimidex) and other treatments that deplete sex hormones
- Letrozole (Femara) used against breast cancer
- Leuprorelin (Lupron) for prostate cancer among other uses.
Recent developments on causes of osteoporosis
Genes for fracture susceptibility and osteoporosis risk discovered. This April 2012 study, published in Nature Genetics, discovered new genetic factors behind osteoporosis.
Osteoporosis clue found in stem cell signalling protein. This stem cell research from August 2012 improves the understanding of osteoporosis.
Signs and symptoms of osteoporosis
The osteoporotic hip is vulnerable to fracture, even from a light fall.
The bone loss that develops slowly in the course toward osteoporosis does not cause any symptoms or outward signs.
The first a patient knows of their osteoporosis may be an unexpected fracture after a minor fall.1,7
A slip or strain - or even a simple cough or sneeze - may result in a fracture. Typical breaks occur in the hip, wrist, or a vertebra collapses in the spine.1,7
These latter breaks in the spine lead to a loss of posture - the stooping appearance that is often seen in older people (a spinal deformity called kyphosis).1,7
Osteoporosis tests and diagnosis
Osteoporosis may be diagnosed directly through the use of a bone scan that measures bone mineral density (BMD).
X-ray technology is used in the scanning, known as bone density scanning or bone mineral density test. Two other names for it are dual-energy X-ray absorptiometry (DXA for short) and bone densitometry.4
Combined with the evaluation of risk factors, DXA offers an indication of the likelihood of fractures occurring due to the osteoporosis. The test is also used to track response to treatment.4
Two devices are available for this scan:4
- Central device - hospital-based scan that measures hip and spine bone mineral density while the patient lies on a table
- Peripheral device - a mobile machine to test bone in the wrist, heel or finger.
The bone density is computed after two X-ray readings - one energy peak that is absorbed by bone and another absorbed by soft tissue, the difference between the two being the measure of bone density. The risk of side-effects from this low-dose X-ray radiation is small.4
The results of the bone mineral density test come as a DXA T-score - a score of not lower than -1.0 is a normal result, while between -1.0 and -2.5 represents mild bone loss.2
Osteoporosis is diagnosed when the T-score is -2.5 or below.
After DXA, the second most common testing option in the US does not involve radiation: quantitative ultrasonography of the calcaneus (heel bone), a method using ultrasound that can also be carried out in the primary care setting. It is not as widely used as DXA, however, and the measurements cannot be compared against DXA T-scores.5
Treatment and prevention of osteoporosis
Fracture risks can be lowered by preventive lifestyle measures against osteoporosis and drug treatments also have a preventive role against bone loss.
The lifestyle measures that help to maintain a healthy bone mineral density and prevent fractures, are:1,2
Calcium is available from certain foods - we need higher intake in old age.
- Get enough calcium (about 1,000-1,200 mg a day, with a higher amount needed by women over 50 and everyone over 70). Calcium is available in the diet or through supplements
- Get enough vitamin D (doctors can help monitor this; sunshine enables vitamin D production, so preventing being housebound helps; it is available from egg yolks, saltwater fish, and liver; the daily recommended amount is 600 international units, and 800 IU in men and women over 70)
- Stop smoking if applicable (this affects a number of factors, including reducing women's estrogen levels)
- Drink alcohol only in moderation (poor nutrition and risk of falls are factors here)
- Exercise - weight-bearing exercise, including simple walking, promotes healthy bone and strengthens support from muscles. Exercises such as yoga also promote posture and balance and so reduce the risk of falls and fractures.
For people who already have osteoporosis, nutrition, exercise and falls prevention play their part in reducing risks and bone loss.3
The drug choices available to prevent and treat osteoporosis include:2,3
- Bisphosphonates - antiresorptive drugs that slow down bone loss and reduce fracture risk
- Estrogen agonists/antagonists (also known as selective estrogen-receptor modulators, SERMS) - for example, raloxifene (Evista) is approved for use in postmenopausal women, for whom it can cut the risk of spine fractures
- Calcitonin (Calcimar, Miacalcin) - also used in postmenopausal women and can prevent spinal fractures, but can also manage pain if fracture occurs
- Parathyroid hormone - for example, teriparatide (Forteo), approved for people with a high risk of fracture, it stimulates bone formation
- Estrogen therapy
- Hormone therapy
- RANK ligand (RANKL) inhibitor - denosumab (Xgeva) is an immune therapy and a new type of treatment in osteoporosis.
Recent developments in osteoporosis treatment and prevention
Vitamin D supplements do not prevent osteoporosis. This study, published in The Lancet in October 2013, found that taking vitamin D supplements did not improve bone mineral density.
Combination drug therapy may be the best treatment for osteoporosis. Results published in The Lancet in May 2013 from an early-stage drug trial raise hopes of improved osteoporosis treatments.
Written by Markus MacGill
