by Stephen Breckenridge
The months of physical and mental preparation had been worth it. I turned 70 on the day three friends and I successfully completed a 10-day, 170-kilometre trek in the Swiss Alps. As we celebrated in the warmth of Chamonix’s late afternoon sun, clouds were building for an alpine blizzard. Tomorrow the route would be buried in snow. We had been lucky to get down.
Five days later, I went to my local doctor, Tim Sutherland, with severe back pain. Dr Sutherland, a fit plain-speaking practitioner of 30 years experience, said, “In medicine there is tendency to pathologise the ageing process. As a consequence there is conflict between good medicine and vested interests. But to be sure you don’t have prostatic or pancreatic cancer that has penetrated the spine, get some bloods done. Then you need a bone mineral density (BMD) test.”
The scans of my hip, pelvis and spine revealed several crushed vertebras. The BMD determined I was osteopaenic, with a mild risk of future fracture.
“Osteopenia is a condition, not a disease. It does not require treatment by a drug, surgery or radiation,” Dr Sutherland said. “Do some research, embrace any beneficial lifestyle change it suggests and continue an active life.”
Along the discovery path, I learnt that osteopenia is part of ageing, the natural degenerative process of bone failure. Because it’s painless it’s rarely detected.
A bone mineral density scan measures the amount of calcium and other minerals in bone. As Osteoporosis Australia says, low levels of BMD do not discriminate between occupation, gender, race, culture or religion. Low BMD occurs among premature babies, infants, coeliacs, men and woman with eating disorders, sports women, young ballet dancers, post-menopausal women, and otherwise healthy adults, including those whose hair is prematurely grey.
Bones produce red and white blood cells and store calcium and phosphorus. When there is a deficiency of calcium and Vitamin D, bones are less dense and prone to fracture.
Bone density changes with age. It reaches its peak level between the ages of 20 and 30, remains stable for a number of years and then decreases rapidly, particularly in men after 50 and in women after menopause.
Almost 20 years ago, the World Health Organisation, acknowledging the need for a basis of case specific comparison, arbitrarily and controversially established an operational definition of osteoporosis, using a surrogate measurement of BMD.
It determined the mean value of a healthy 30-year-old white female’s BMD and plotted it on a graph. Levels of BMD above it were considered normal. Those between -1 and -2.5 places below were defined as Osteopenia. Places below -2.5 were defined as Osteoporosis.
The most common and accurate BMD test uses a scanner which moves over the spine and hips. It is considered the best test of predicting fracture risk. Another smaller machine measures BMD in wrists, fingers, legs and heels.
The measurements are expressed as a T score, but they are not static. Healthy bones continually remodel and reabsorb calcium, so the T score is a continuous measurement.
The British Medical Journal, among others, carried criticism that the WHO definition was flawed in its August and September 2000 issues. Experts thought factors other than BMD were just as, if not more, relevant. Subsequently, the WHO developed a Fracture Risk Assessment Tool (FRAX) with 12 risk factors to estimate the chance of breaking a bone within the next 10 years.
In 2008, Sydney’s Garvan Institute of Medical Research developed a prognostic tool, the Garvan Fracture Risk Calculator, that enables the risk of fracture within five and 10 years to be determined. It is based on only five risk factors: gender; age; BMD; body weight; history of fracture and falls.
At the time of the launch of the calculator, Professor Tuan Nguyen, Senior Research Fellow in the Bone Research Program at the Garvan Institute, whose team developed the tool, said, “We can see very clearly that our model predicts fractures at least as well as the WHO model when applied to an Australian population, and apparently more accurately for Australian men.”
Recently he said that study after study “consistently saw that the Garvan Fracture Risk Calculator is better than the FRAX model”.
As osteopenia, unlike osteoporosis, is not indicated for treatment, the Government will not support doctors testing for it, despite the obvious benefit.
However, Professor Nguyen says, “I think it is economically justified to do early screening. It is not possible to prevent bone loss and it is not possible to reverse it. You can still preserve your bone density at a safe level.”
Strategies to slow down the rate of bone mineral loss include physical activity and attention to diet. Both the Garvan Institute and Osteoporosis Australia publish guides that says weight-bearing exercise such as walking, dancing and weight training are appropriate. And balance, muscle strength, elasticity and reflexes provide reactive agility to recover in the event of a trip, preventing a fall and the risk of fracture.
At a dietary level, key factors include sufficient intake of calcium and exposure to sunlight to produce Vitamin D. Limiting salt, caffeine, steroids, alcohol consumption and avoiding smoking are important.
Where dietary intake of calcium is low, supplementation may be beneficial. Vitamin D supplementation has been rising in Australia.
However, while on the current evidence the benefits still outweigh the risks, Professor Nguyen points to some recent evidence that calcium and vitamin D supplementation can increase the risk of cardiovascular disease.
Early studies by the Garvan Institute have discovered that in mice the brain is capable of sensing the loss of bone density and regulating the cells inside the bones to produce more. According to Professor Nguyen, this may have a major implication for development of a drug for treatment in 15 years.
In the interim a good lifestyle, positive and supportive mental attitude may be the key to dealing with osteopenia.
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