While women have a higher risk of developing osteoporosis, it can affect men as well. In this article, Prof Richard Prince (Endocrinology Specialist Physician) explains what men and women can do to manage osteoporosis and reduce their risk of fracture.
What causes osteoporosis?
Osteoporosis is a broad term meaning holes in the bone and applies to progressive disorders that share the same appearance but can result from many causes. Inside our skeleton, some cells called osteoclasts are eating out the old bone. A different set of cells called osteoblasts replace the lost bone with new bone. This is occurring all over your skeleton throughout life to provide new, repaired, strong bone.
Unfortunately, as the bone forming cells (osteoblasts) get older, they become less active and cannot keep up with the bone-eating cells (osteoclasts). Hence our skeletons develop holes. The good news is that we know a lot about these two types of cell and can improve the balance between them. In some cases, we can build a skeleton better than it used to be.
Where to start? Bone structure
The risks of fracture are often of interest to people living with osteoporosis. The internal construction of our bones is one factor involved in determining this risk. Another factor is the thickness of the outermost bone layer the cortical bone. Big bones with the same total amount of cortical bone as small bones are stronger in bending. This why architects put a hole down the middle of a column. The good news is that bone density (DXA BMD) includes both, and so remains the best predictor of fracture risk. Hence, one simple, cheap, low radiation test can tell us whether you have osteoporosis with lots of holes and what your risk of fracture may be.
In terms of fracture risk, age is also important. As we age, our bones develop more holes, and we fall over more, hence our risk of fracture increases. The good news is that both of these factors can be addressed, so fracturing is not necessarily an inevitable outcome of ageing.
If you and your doctor want to find out if you are at risk of osteoporosis, start with a good quality bone density test at the hip and spine. Unfortunately, not all bone density services will provide sufficient information to enable your risk to be accurately evaluated. Specifically, not all services offer you your bone density pictures. Receipt of these pictures is essential to aid accurate evaluation of the results. Hence, you should ask your bone density service if they will supply you with your images. Always take these images to your doctor to ask them to explain what they mean.
What is going on?
If you are at risk of osteoporosis or unexpected fragility fracture, you need to understand how to reduce the rate of bone loss. To achieve this, the activity of the bone eating osteoclasts should be diminished and the activity of the bone forming osteoblasts should be increased.
Regarding osteoclasts, in both men and women, the hormone estrogen reduces their eating activity. However, after menopause, the estrogen level in women falls below levels that reduce osteoclastactivity and hence, bone is lost. Another reason that osteoclasts eat bone is to release calcium into the circulation to keep the levels constant.
Regarding osteoblasts, as they age, their activity falls. The reasons behind this are complicated and relate to the loss of stem cells from where they grow. However, if they are provided with the right stimulus, such as appropriately prescribed exercise, these cells wake up and make more bone. They can also grow to fix fractures if necessary. Therefore, they could be regarded as sleepy rather than lazy.
What can you do?
To prevent your osteoclasts from being overactive, you must consume about 1200mg calcium per day. To correct this, you may need to increase your calcium intake from your food or take a 600 mg calcium tablet every day for the rest of your life. Vitamin D is an essential nutrient to help to absorb calcium from the intestine; to be safe you need at 800-1000IU per day. In Australia, we tend to purposely avoid sun exposure due to the associated risks of skin cancer, but in doing so; we limit the vitamin D manufacture in the skin. Fortunately, you can absorb vitamin D from your food. However, it is challenging to eat enough vitamin D containing seafood, as many do not like cod liver oil; also 1000mg only contains 100IU. Thus if you are at risk of osteoporosis, you need to boost your vitamin D levels with a supplement of approximately 1000IU vitamin D per day as a tablet.
We should all be exercising to improve our body systems, including the musculoskeletal system. Exercise can take on many forms, but with regards to osteoporosis, there is good evidence for strength training. Specifically, exercise management for osteoporosis needs to emphasize high-load resistance exercise under the guidance of an appropriately qualified health professional. For people who have sustained a vertebral fracture, a tailored exercise prescription is provided by an accredited physiotherapy or exercise physiology assessment and treatment program.
What about falling?
As we age, we fall over more, which exposes our skeleton to forces that they are not designed to withstand. For example, falling on your outstretched hand causes strong bending forces at the wrist in a direction the bone is not exposed to normally hence it may break.
If you cannot stand for 10 seconds on each foot, preferably with your eyes closed, you may be at risk of falling. If you have already fallen over because of loss of balance, you should consider talking to your GP or Physiotherapist about undergoing a falls assessment and engaging in an appropriate balance training and exercise program to help reduce your risk of falling.
What can you and your doctor do together?
Your doctor can advise you about several very effective pharmaceutical treatments available that can increase the strength of your skeleton and reduce the risk of fracturing. These treatments can reduce fracture risk by about half. They need to be taken for life because osteoporosis is like high blood pressure or diabetes; it does not go away.
Anti-bone eating osteoclast treatments – Estrogen is a useful anti-osteoclast treatment; however, due to the side effects in women past menopause, it is no longer used as much as previously. In men with low testosterone, treatment with this hormone that gets converted to estrogen that also improves bone structure and strength.
Once the overactivity of osteoclasts is managed, the holes they have left on the surface of the bone get filled in by the bone-building osteoblasts – so the bone mass and strength go up.
Bisphosphonates – This is the chemical name for a group of drugs (e.g. Actonel, Fosamax or Aclasta) that stick to the bone and reduce osteoclast eating activity. There are a large number of confusing trade names so it is best to learn the chemical names (risedronate, alendronate or zoledronic acid) so you know what you are getting. They have been in use for 30 years and are effective in slowing bone loss. They can be given by a tablet one a week or once a month or by an injection into your vein, given every 2 – 3 years.
Denosumab – This is the proper chemical name for a drug that has been marketed for about ten years, the trade name is Prolia. It is given every six months by an injection under the skin, much like an immunisation. Because of its short term action, it is essential not to miss the six monthly injection. Denosumab works in a completely different way to bisphosphonates by blocking a chemical signal in the circulation that tells the osteoclast to eat faster. The denosumab sticks to it before it can stick to the osteoclast, so the osteoclast reduces its activity.
Adverse effects – Everything we do, including using pharmaceuticals, may have adverse results. So the question is – what are the risks? Short term bisphosphonates taken by mouth may cause indigestion, if so, you should stop. Denosumab can very occasionally cause dermatitis to get worse.
Long term, the risks are of non-healing of a wound in the jaw often after a tooth extraction. Providing dental surgery is done well and infection is prevented, the risk is less than 0.1%. That is less than the risk of ending up in hospital as a result of a motor vehicle accident per year. You must, of course, tell your dentist about this treatment.
The second even more uncommon problem is of developing a stress fracture on the outside of the bone in your upper leg, the femur. This causes localized pain in the area and can proceed to a fracture. So if after about 3 or 4 years of taking bisphosphonates you develop thigh pain, you should see your doctor who may order an isotope bone scan to evaluate the bone as it is more sensitive than an x-ray.
Stimulating bone formation with anabolic therapy
We can now help osteoblasts make new bone with use of a drug called teriparatide (Forteo). The PBS will reduce the cost of up to $7500 if you meet the strict criteria of continuing to fracture on anti-bone eating osteoclast treatment. However, it can also be prescribed privately for those who can afford it. If you think this treatment may help, you should ask your doctor to refer you to someone who is an expert in advising on this therapy.
In conclusion non-cancerous bone disease related to osteoporosis is treatable and preventable if you take some time to understand it.