Boning up on bone health
A common misconception is that osteoporosis is a woman's disease, to the extent that it's often overlooked in men. However, one-third of all hip fractures worldwide occur in men, with mortality rates as high as 37% in the first year following the fracture. Men are likely to be older than women when they suffer their first osteoporotic fracture, and are twice as likely as women to die after a hip fracture.
With our ageing population, osteoporosis is becoming more and more prevalent in Australia. But taking action in middle age can help diagnose potential bone health issues, and prevent them from getting worse later on.
Osteoporosis literally means 'porous bones': bones that are not as dense and strong as they should be, making them easier to fracture, or in the spine to compress. Visible signs include spine deformities, such as 'dowager's hump', and decreasing height.
But the main concern with osteoporosis is the relative ease with which fractures occur, impacting on quality of life and independence – and, in the case of hip fractures, linked with premature death.
- Increasing age
- A family history of osteoporosis or fractures in old age
- Asian or Caucasian ethnicity
- Taking certain medications long term, such as corticosteroids (for treatment of asthma or allergies), anticonvulsants, antacids that contain aluminium, heparin and thyroid hormone replacement
- Low body weight for your age and height – you're more likely to have low bone mineral density and less 'padding' (fat and muscle) for protecting bones if you fall
- Low hormone levels – oestrogen for women, especially around menopause, and testosterone for men
- Women who experience an early menopause
- Poor nutrition, including not enough calcium and too much salt and caffeine
- Excessive alcohol (more than two or three standard drinks per day)
- Sedentary lifestyle
- Low levels of vitamin D
The earlier osteoporosis is picked up, the better. Experts recommend men and women over 50 with osteoporosis family history and lifestyle risk factors have a bone check-up with a bone density scan; people with certain medical conditions and on medications that increase risk of osteoporosis may be recommended for screening at a younger age. For people with no other risk factors, a scan at age 70 is recommended.
So how do you know if you have it?
Dual-energy x-ray absorptiometry (DXA or DEXA) is considered the gold standard of bone density measurement. Your results are based on the bone density of the hip and spine, and are usually presented as a T-score, which compares your bone density with that of a healthy young adult of your gender.
A negative score means you have less dense bones than average, with a diagnosis of osteoporosis at -2.5 or below, and osteopaenia (which may lead to osteoporosis) between -1 and -2.5. This is then used in conjunction with other risk factors to determine your fracture risk score and whether further action is needed in terms of follow up or treatment.
There are Medicare rebates for bone densitometry:
- where a patient has certain specific medical conditions or is undergoing particular treatments likely to cause rapid bone loss;
- to confirm suspected low bone mineral density, usually following a fracture;
- for the subsequent monitoring of established low bone mineral density; and/or
- for patients over 70 years old.
T-scores from a whole body DXA – which is increasingly popular for measuring body composition for weight loss or muscle gain – doesn't reliably predict fracture risk. This is because determining fracture risk is based only on the T-scores for the hip and spine; a whole-body bone density score tends to underestimate the prevalence of osteoporosis.
Trabecular bone score (TBS)
When it comes to fractures, bone density doesn't tell the whole story; the quality of bone structure also has bearing on the risk of fractures. Trabecular bone score (TBS) is a new measure of the bone's quality, providing information about the texture of the bone and its architecture.
According to Dr Weiwen Chen, who's involved in research on TBS, it's most useful for people with T-scores bordering osteopaenia and osteoporosis.
"Sometimes people with bone density scores that seem OK suffer a fracture – the TBS can give an indication of the architecture of the bone, and may be able to predict fracture risk more accurately than bone density alone," says Dr Chen.
The TBS can be useful in conjunction with the T-score in some patients. So someone with a low T-score and a low TBS is more at risk of fracture than someone with a low T-score and high TBS.
It doesn't require an extra test – TBS is measured from a standard lumbar spine DXA image using proprietary software. It's only recently been introduced and there's no consensus on its role. However, the number of imaging centres measuring TBS is increasing throughout Australia.
Sometimes offered in pharmacies, ultrasound of the heel doesn't produce a reliable bone density score. While it may be indicative that further investigation is needed, it's not as precise as DXA and therefore not recommended.
Falling through the cracks
Unfortunately for many people, the first sign of osteoporosis comes with a broken bone, usually from something low impact like simply falling while standing up. After hospital treatment for the fracture, there is often no further follow up to determine why the fracture occurred in the first place – which could show whether the person in question actually has osteoporosis. That in turn means there are no measures put in place to prevent future fractures.
Various programs are underway to increase collaboration between the hospitals treating fractures and the patient's own doctors – Capture The Fracture is an international awareness program, promoting the establishment of Fracture Liaison Services (FLS) in hospitals.
Until FLS rolls out more widely, consumers could pursue follow-up for such fractures in themselves or family members.
What's your risk of fracture?
The World Health Organisation Fracture Risk Assessment Tool – FRAX – will estimate your risk of fracture based on lifestyle, medication and family history, and bone density score (if you have it).
Apart from healthy lifestyle in general – no smoking, good diet, regular weight-bearing exercise, alcohol within recommended guidelines – the main preventative steps you can make toward preventing osteoporosis is ensuring you have adequate calcium and vitamin D.
Do you need a calcium supplement?
Calcium plays a critical role in bone growth and maintenance, and it's important to include good sources of calcium in your diet. Teenagers, women over 50 and men over 70 need the most – those groups are currently recommended to get 1300mg per day.
However, calcium supplements recently hit the headlines for all the wrong reasons when research suggested they were linked with increased risk of heart attack, stroke and other cardiovascular diseases. While these findings are cause for concern, the data are inconsistent, and more research is needed.
It's worth noting this only applies to calcium supplements, and not to dietary sources of calcium, such as dairy, fish bones and leafy green vegetables. If dietary calcium is low, Osteoporosis Australia recommends a supplement of 500-600mg per day, which is considered safe and effective.
Do you get enough vitamin D?
When it comes to bone health, Vitamin D is closely linked with calcium because it aids its absorption, and reduces calcium loss from bones. Our main source of vitamin D comes from exposure to sunlight, with other minor sources being fatty fish, eggs, meat, fungi and fortified foods.
Studies among the general population in Australia have found that over 30% of adults have vitamin D deficiency. Some people are at higher risk of deficiency, including people with little or no sun exposure, people with naturally dark skin, obese people, older people and people with certain conditions that mean reduced vitamin D absorption and/or synthesis.
If you're at risk of or have a vitamin D deficiency, discuss your options with your doctor – they may recommend a test, and you may need a supplement. Vitamin D supplements are cheap, at around 10-16 cents per day, and usually come in a dose of 1000IU.
There are many effective medicines to prevent and reverse osteoporosis, and the one your doctor recommends will depend upon your age, sex and medical history, including your current bone health and fracture history, and other conditions you may have. Most are subsidised by the PBS only for people who have experienced fragility fractures, or are people over 70 at risk of fractures due to low bone density.
One of the challenges in treating osteoporosis is getting patients to take their prescribed medicine. There are several issues, including the long-term nature of many treatments with no obvious benefits, the inconvenience of some treatments (such as having to stay upright after taking bisphosphonates) or unpleasant side effects (such as heartburn or flu-like symptoms). There are some treatment options that require only occasional dosing, such as zoledronic acid (see Bisphosphonates, below) or denosumab, which overcomes some of these issues.
Hormone replacement therapy (HRT)
In addition to helping with symptoms of menopause, HRT has been shown to prevent bone loss in early menopause. There's a slightly increased risk of heart disease, stroke and breast cancer in women over 60, so other osteoporosis treatments should be considered. In younger women, it shouldn't be used primarily for fracture prevention. Your doctor can help you weigh up the risks and benefits of HRT.
Hormone replacement also appears to reduce bone loss for men with low testosterone, though fracture reduction hasn't been shown and risks may outweigh benefits.
Selective oestrogen receptor modulators (SERMs)
SERMs are chemicals that mimic oestrogens in particular parts of the body. Raloxifene (brand name Evista) is approved for osteoporosis in Australia, and works by slowing bone loss and reducing the risk of spinal fractures.
Bisphosphonates are phosphorus compounds that prevent breakdown of bone. Alendronate (Fosamax and generic) and risedronate (Actonel and generic) are taken daily, and there's also an intravenous version called zoledronic acid (Aclasta) which is administered once a year.
Strontium ranelate (Protos) is absorbed into the bone in a similar way to calcium. It increases bone formation and reduces bone loss, creating denser and stronger bones over time. It comes in a powder form, to be dissolved in water daily.
Denosumab (Prolia) slows the rate at which bone is broken down by inhibiting the protein that signals bone removal. It's available as a six-monthly injection.
For severe forms of osteoporosis, your specialist may prescribe teriparatide (Forteo) injections. They're self-administered daily for 18 months. It works by stimulating bone-forming cells, improving bone strength and structure.