Dr Kevin McCarrollMany factors can lead to diminished bone strength but ‘addressing lifestyle factors will be the first port of call’ for prevention
Osteoporosis or ‘brittle bones’ is the commonest bone disorder that often only comes to attention after a fracture from a fall in later life. While predominantly occurring in older females, it can affect adults of any age and gender.
It is characterised by reduced bone mass and increased bone porosity, leading to diminished bone strength and increased susceptibility to fractures.
In Ireland, it estimated that 200,000 adults have osteoporosis, and that one in two females and one in five males over 50 will suffer an osteoporotic fracture in their lifetime. As more people are diagnosed with osteoporosis, there is an increased awareness of its risk factors and the importance of lifestyle in maintaining healthy bones. So what is it that makes our bones brittle and what can be done to treat or prevent it?
Just as we replenish our skin, our bones are in a constant state of breakdown and build up, such that every ten years all of our bone will have been remodelled.
This process removes old bone and its micro-cracks and allows it to be replaced by healthier new bone. However, if this becomes imbalanced bone breakdown may exceed its replacement giving rise to osteoporosis.
This occurs classically in the first few years after the menopause due to the loss of oestrogen, and accounts for the higher prevalence of osteoporosis in females.
However, several other factors negatively affect bone remodelling including smoking, alcohol and caffeine excess, sedentary lifestyle, low body mass, poor diet with low calcium intake and vitamin D deficiency.
Medical conditions account for a small proportion of all cases of osteoporosis and include some chronic inflammatory and endocrine disorders, as well as certain bone and haematological diseases. Some medications can accelerate bone loss and cause brittle bones, especially steroids.
Finally, there is also a significant genetic component, and having a family history of osteoporosis or a close relative with a hip or low trauma fracture will increase the risk.
As osteoporosis is a ‘silent’ disease and does not give rise to pain, it is often diagnosed following a hip, wrist or vertebral fracture (as result of a simple fall).
Spontaneous fractures of the vertebrae may also occur and present with acute back pain or be painless and cause loss of height or a hump to develop.
When fractures present as above, they are considered to result from osteoporosis until otherwise proven. However, a formal diagnosis is usually made with a DXA (dual-energy x-ray absorptiometry) test which measures bone mineral density in the spine and hip. This is widely available and inexpensive (it costs approximately €100).
When bone mineral density is in the intermediate range between normal and osteoporosis, one is said to have osteopaenia.
Due to the high prevalence of osteoporosis in older adults, screening with DXA is recommended for all women aged 65 or older and should also be considered for men aged 70 or older. In addition, anyone with a fracture (due to minor trauma) or who has significant risk factors for osteoporosis should consider having a DXA.
Regardless of whether you have osteopaenia or osteoporosis, addressing lifestyle factors will be the first port of call. This is also important in maintaining healthy bones in general. Indeed, as peak bone density is reached in our early to mid-30s, having a healthy lifestyle when younger lays the foundation for good bones.
Regular weight bearing exercise which stimulates new bone growth is recommended and can take the form of walking or jogging on the spot for at least for 30 minutes a day. Avoidance of smoking and taking alcohol in moderation is also advised.
An adequate intake of calcium is essential to ensure mineralisation of our bones. Calcium obtained naturally from the diet is preferable as it is better absorbed, but supplemental calcium is often required to make up the total recommended daily intake of between 1,000 and 1,200 mg.
This equates to a few portions of dairy produce a day (cheese, yogurt or a glass of milk each contain about 200-250 mg of calcium) though other rich food sources include green vegetables, nuts and oily fish. Low-fat dairy alternatives are a good option if high cholesterol is a concern.
Ensuring adequate vitamin D status is also crucial as it is required for optimal gut absorption of calcium. Supplementing with at least 800 IU daily is recommended if you have osteopaenia or osteoporosis, though a higher daily dose of up to 2,000 IU is prudent in the winter months. Tablets combining calcium and vitamin D are readily available and are routinely prescribed.
If you have osteopaenia with fractures or osteoporosis, you will usually need to go on additional treatment to strengthen your bones.
The choice of drug used will depend on the severity of osteoporosis, fracture risk, other medical factors and personal preference. The mainstay of treatment includes the option of a once-weekly tablet, twice-yearly injection or a once-yearly infusion.
Injection
In addition, a daily subcutaneous injection of a natural hormone derivative over a two-year period can directly build up new bone, and is used in more severe cases of osteoporosis, particularly with vertebral fractures.
The above treatments substantially reduce fracture risk and for some may even bring bone density back to a normal level. Follow-up assessment with DXA is often performed to monitor response to treatment, as well as guide treatment duration.
While the ultimate aim of treating osteoporosis is to prevent fractures, avoiding or preventing falls is also a crucial part of achieving this goal. If you have brittle bones, then any activity which might lead to significant trauma or falls should be avoided!