Osteoporosis can affect anyone of any gender, but it is particularly prevalent in postmenopausal women due to the sudden decrease in protective oestrogen levels after menopause.
Contents of this article:
What is osteoporosis?
The components of the word 'osteoporosis' literally mean 'porous bones' - 'osteo' is for bones, and 'porosis' means porous - helpfully describing this condition that results in reduced bone density and increased fragility of the bones.1
The thinning of the bones in osteoporosis, combined with the formation of weaker bone crystals, puts people at a higher risk of fractures.3,4
Although osteoporosis itself does not directly increase the risk of falls, people who have osteoporosis have a higher risk of breaking a bone if they fall, with common sites of fracture including the hip, spinal vertebrae and wrist.2
Osteoporosis results in a loss of bone mineral density and a higher risk of fractures.
Osteoporosis can affect people of any gender, but women make up the majority of cases, and over 40 million people in the US 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 put 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 found 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 of bone, raising the risk of fractures.
- Postmenopausal women are most likely to develop the condition, but it also affects men and younger people across all genders.
- Some risk factors for osteoporosis are modifiable, such as smoking and poor nutrition.
- Osteoporosis is often considered a silent disease as there are no clear outward symptoms caused by the loss of bone density (although bone pain may occur in some people).
- Fractures are most likely in the spine, hip and wrists.
- Diagnosis is made directly via a special X-ray-based scan, and sometimes through ultrasound.
- Treatments include drugs that prevent or slow down bone loss, exercise programs, and dietary adjustments, including extra calcium, magnesium and vitamin D.
- It is important for people with osteoporosis to take measures to avoid falls so as to reduce the risk of fractures (which can prove fatal).
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
- Ethnicity - risk is higher in white people and Asians
- Bone structure - risk is higher in those with small bone structure
- Genetics - risk is higher if there is osteoporosis in the family, especially if a parent or sibling has the disease, particularly if a parent has incurred a hip fracture
- Fracture history - risk is higher in people with a previous fracture during a low-level injury, especially if this occurred after the age of 50.
Although we often think of our bones as being static, these tissues are in constant turnover, with old damaged bone replaced by new bone to maintain bone density, and the integrity of its crystals and structure.9 However, as we age, the rate of bone breakdown can outstrip bone-building, with a peak in bone density in the late twenties, and a gradual weakening after the age of 35 or so; in some people, this natural weakening is more pronounced, leading to osteoporosis and a higher risk of fractures.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), and orthorexia
- Tobacco smoking
- Excessive alcohol intake
- Reduced calcium, magnesium and vitamin D status (caused by low dietary intake, malabsorption, and the use of some medications)
- Inactivity or immobility (weight-bearing exercise that places a degree of stress on the bones is needed for bone growth).
Other factors that increase the risk of osteoporosis include diseases or drugs that cause changes in hormone levels, and drugs that reduce bone mass.2,7 Diseases that affect hormone levels include hyperthyroidism, hyperparathyroidism and Cushing's disease.
People who are transgender and who undergo surgery that affects hormone levels, or who take hormones for long periods of time may also face a higher risk of osteoporosis.10 Some autoimmune diseases, such as Rheumatoid arthritis and ankylosing spondylitis, are also associated with an increased risk of osteoporosis.2
Medications that increase the risk of osteoporosis include:2
- Glucocorticoids and corticosteroids, including prednisone (Deltasone, Orasone, for example) and prednisolone (Prelone) - glucocorticoid-induced osteoporosis is the most common type of drug-induced osteoporosis
- Excess thyroid hormone replacement
- Anticoagulants and blood-thinners (including heparin and warfarin)
- Protein-pump inhibitors and other antacids that adversely affect mineral status
- Some antidepressant medications
- Some vitamin A (retinoid) medications
- Thiazolidinediones (used to treat type 2 diabetes), which decrease bone formation
- Some immunosuppressant agents, such as cyclosporine, which increase both bone resorption and formation
- Aromatase inhibitors and other treatments that deplete sex hormones, such as anastrozole (Arimidex)
- Some chemotherapeutic agents, including letrozole (Femara), which is used against breast cancer, and leuprorelin (Lupron) for prostate cancer (and other conditions).
Recent developments on causes of osteoporosis
This April 2012 study, published in Nature Genetics, discovered new genetic factors behind osteoporosis.
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.
Bone loss that develops slowly, leading to osteoporosis, does not cause any symptoms or outward signs.
As such, a patient may only discover that they have osteoporosis due to 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. Typically, breaks occur in the hip, wrist, or in the spinal vertebrae.1,7
Breaks in the spine can lead to altered posture, with compressed vertebrae creating the stooped appearance often seen in older people (this excessive curvature of the spine is 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 for bone density scanning, also known as a bone mineral density test, dual-energy X-ray absorptiometry (DXA for short) and bone densitometry.4
In combination with a determination of a patient's risk factors, DXA offers an indication of the likelihood of fractures occurring due to osteoporosis. This test is also used to monitor response to treatment.4
Two types of device are available for a DXA 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.
Two X-ray readings are taken to ascertain bone density - one to detect peak energy absorbed by bone and another for energy absorbed by soft tissue - the difference between the two gives a measurement 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 are given as a DXA T-score; -1.0 or above is considered normal, while a DXA T-score 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) uses ultrasound and can 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
The risk of developing osteoporosis and/or incurring a fracture can be lowered by preventive lifestyle measures and drug treatments that protect against bone loss and encourage healthy bone mineralization.
Lifestyle measures that help to maintain a healthy bone mineral density and prevent fractures include:1,2
Calcium is available from certain foods - we need higher intake in old age.
- Ensuring adequate calcium intake (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
- Ensuring adequate vitamin D status (doctors can help monitor this, and supplements may be necessary for anyone who is housebound, has very dark skin, little sun exposure, or who lives at a more northerly latitude; vitamin D is synthesised through the action of sunlight on skin, and is available in the diet through fortified foods, 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 the growth of new bone and decreasing women's estrogen levels)
- Drink alcohol only in moderation (elevated alcohol intake is also associated with other risk factors, such as poor nutrition and an increased risk of falls)
- 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 fall prevention play a key role in reducing risks and bone loss.3
Drugs that are currently 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 to prevent spinal fracture in postmenopausal women, as well as to manage pain if fracture occurs
- Parathyroid hormone - for example, teriparatide (Forteo), approved for people with a high risk of fracture as it stimulates bone formation
- Estrogen therapy
- Hormone therapy
- RANK ligand (RANKL) inhibitor - denosumab (Xgeva) is an immune therapy and a new type of osteoporosis treatment.
Recent developments in osteoporosis treatment and prevention
While the findings are early, scientists are hopeful that bone loss disease could find a new treatment after their lab work succeeds in increasing the formation of bone. Their work has been published in the journal Nature Communications.
Growth hormone treatment has sustained effects against problems associated with osteoporosis for years after it is stopped in postmenopausal women, suggests a new trial.
A diet rich in the types of protein and isoflavones found in soybeans may protect women undergoing menopause against bone loss and osteoporosis.
A single injection of stem cells could one day restore normal bone structure in patients with osteoporosis, say researchers who achieved this reversal in mice. The findings are published in Stem Cells Translational Medicine.
Vitamin D supplementation appears to help improve bone mineral density in people with low levels of vitamin D, especially for people with Klinefelter syndrome and those taking glucocorticoids.15 In one review, the authors concluded that vitamin D supplementation alongside adequate calcium had a small beneficial effect on bone mineral density.14
Another study found that vitamin D fortification of bread eaten by older adults in residential care facilities led to an increase in vitamin D status and increased bone mineral density.17 Studies have also shown that a lack of vitamin D supplementation is associated with decreased bone mineral density in adolescent girls with juvenile systemic lupus erythematosus, and that vitamin D supplementation may also help decrease mortality in older adults.12,13