Osteoporosis: 'the brittle truth!'
“Our frames humbled as the hourglass pours, and alas like children, vulnerability restored”.
This article is supposed to provide a brief overview of the condition Osteoporosis.
With respect to each individual, it is advisable for any personal questions or concerns to be brought up with their GP (General Practitioner), especially considering the continual update of research into treatments.
What is Osteoporosis?
Osteoporosis can be defined as a disorder of diminished bone density and degeneration of the microarchitecture of the bone matrix, eventually leading to brittle bones, which are vulnerable to breaks (fractures) if subjected to minimal trauma. This could be sustained simply from a low impact injury (like a fall from a standing position onto the floor), resulting with a broken bone (a fractured hip for instance). These types of low-impact fractures are otherwise known as Fragility fractures.
Basic Anatomy (Very brief!)
Bone is comprised of three cardinal building blocks - collagen fibrils, mineral plates, and a matrix of unmineralized, non-fibrillar organic material, mostly made of glycoproteins (compounds of protein and carbohydrate). If you look at a bone sample under an electron microscope, you should be able to see a complex ‘criss-cross’ mesh network of these fibrils. It is this layout, which allows forces to be transferred in multiple directions, allowing us to resist the varying daily stresses imposed on it.
Due to this property, it makes our skeletons robust structures, thus allowing us to perform weight bearing tasks, maintain posture, and protect our vital organs (such as our heart and lungs behind our rib cages), with less threat of damage to minimal trauma.
Now, if we were to compare this microscopic image with the bone sample from a woman in her eighties’ with osteoporosis, it should be apparent that there is a significant loss in the bone mineralisation.
It is this loss in the Bone Mineral Density (BMD), which accounts for the confirmation and complications of osteoporosis.
How common is osteoporosis?
The answer to this is straight forward...extremely common!
As this condition is a naturally progressing degenerative condition, it is pandemic, and affects people of all nationalities across the globe.
Only in the United Kingdom (UK) in 2006, was it reported to have caused over 200,000 fractures each year.
The ratio is higher in women as they lose the bone-protecting factor of oestrogen once the menopause is reached and the ovaries become less receptive to the hormones that stimulate ovulation (egg production), and hence oestrogen production. This loss accounts for over one-third of women in the UK having an osteoporotic fracture in their lifetime, which compares to men having a lower risk of one in twelve of suffering such a fracture.
Who is at risk of getting osteoporosis?
It is impossible to determine whether you will definitely develop osteoporosis, as people generally get the natural ‘thinning’ (loss of minerals) of bone with age, which can render us more susceptible to breaks with injuries that were once escapable from fracture in youth. As this condition is more a deterioration from the normal progressive spectrum of age related bone degeneration, there are three main stages of bone degeneration: 1) normal (age-related bone demineralisation), 2) Osteopenia (Reduction in bone mass, usually caused by a lowered rate of formation of new bone that is insufficient to keep up with the rate of bone destruction, but not as severe as osteoporosis-more the ‘diet coke’ stage of osteoporosis, and then finally 3) Osteoporosis, which is a severe loss of bone mineral density, which has precarious clinical consequences.
Ok! then, what can put us at a higher risk above the average population?
Those who are at an increased risk of developing osteoporosis are:
-The frail and elderly, who have an increased risk of falls, whether housebound or not.
-Those with major risk factors, such as: premature menopause (loss of protective oestrogen), secondary amenorrhoea (cessation of menstrual periods after establishment of puberty-for example anorexia nervosa, deficiency of pituitary, thyroid or ovarian hormones etc). And primary or secondary hypogonadism (impaired function of the testes causing absence or impairment of the development of secondary sexual characteristics) in men.
-Prolonged steroid therapy: this can predispose to osteoporosis.
-Evidence of bone thinning on imaging, for example X-rays of the spine showing decrease in bone contrast or old vertebral fractures that could implicate Osteopenia, or undiagnosed osteoporosis.
-Those with a previous fragility fracture.
What diagnostic test is available to detect osteoporosis?
One of the main imaging techniques is a DEXA (dual energy X-ray absorptiometry) scan, which specifically measures bone mineral density (BMD).
This scanner will calculate the BMD at multiple sites.
Now, as mentioned previously, BMD follows a spectrum with age, thus it follows a standard normal ‘bell shaped’ curve distribution.
It will then compare the individual result to the mean result of an average healthy young adult male/female, depending on the gender being tested.
By using these standard deviations, cut-off groups for diagnosis have been created. The ranges for which have been determined after looking at studies, comparing the incidence of fractures in adults with their BMD's falling in these ranges.
These values (or standard deviations below the average) are referred to as the ‘T-Score’.
· T score above-1=normal
· T-score between -1 and 2.5=Osteopenia
· T-score below -2.5 standard deviations below the young adult mean=Osteoporosis
Patients who are in the high-risk group, or have had a fragility fracture that could indicate osteoporosis are usually good candidates for this scan.
Sometimes patients won’t be necessarily scanned, particularly if they have obviously had an osteoporotic fracture clinically and are already in the ‘high risk’ category; their GP may empirically start them straight away on bone-protecting medication.
Other tests your GP may do to investigate the bone status are blood and urine tests, and possibly X-rays of the spine, again depending on the individual needs.
What if I don’t have osteoporosis, can I still have these ‘bone- protecting’ medications?
Unfortunately, the medication for osteoporosis is quite potent with potential side effects; it has strict instructions on what times to take it, and can be quite costly to the health service.
So it should only be reserved for those people with confirmed osteoporosis (either clinically or on radiological imaging), who have a real need for these drugs.
Can I do anything to help prevent getting this condition?
YES! There is plenty of research that has proven that regular exercise and a good dietary intake of calcium is bone-protective. Try eating foods with rich sources of calcium, for example: cheddar cheese (216mg per 30g), milk (237-249mg per 200ml glass-depending on whether whole or skimmed), and low fat fruit yoghurt (225mg per 150g pot), and much more!
The biochemical processing of calcium does involve the liver (whereby vitamin D is converted to 25-hydroxy vitamin D) before going to the kidneys for further processing, thus refraining from excessive alcohol aids calcium absorption.
The cessation of smoking assists in bone protection.
Since calcium absorption relies on dietary intake, exposure to sunlight and absorption through good organ function (i.e. kidneys), other calcium supplements may be required for certain patients. These can be provided for patients with kidney disease, reduced intake in frailty, or those who may not have as much skin exposure to natural sunlight due to religious beliefs.
It should be noted that those at risk of osteoporosis should maintain an adequate intake of calcium and vitamin D, and any deficiency should be corrected by increasing dietary intake or taking supplements.
If I had osteoporosis, what treatments are available?
One of the main treatments is Bisphosphonates. These are absorbed onto hydroxyapatite crystals in bone, slowing both their rate of growth and dissolution, and therefore reducing the rate of bone turnover.
Bisphosphonates have been shown to reduce fracture rates at all sites (spine, hip and elsewhere).
They are often taken once a week, however they can be administered every 3 months via an infusion, and now there is even an annual infusion option (particularly for patients with disorders of calcium metabolism) of the bisphosphonate, Zoledronic acid (trade name ‘Zometa’), which has the bonus of improving compliance. However, there are more side-effects with this annual option, which requires close monitoring.
With regards to the oral weekly preparations; one of the main side-effects is gullet (oesophageal) irritation, which is why there are strict instructions for tablets to be swallowed with plenty of water while sitting or standing; to be taken on an empty stomach at least 30 minutes before breakfast (or another oral medicine), and the patient should stand or sit upright for at least 30 minutes after taking the tablet.
If patients report any reflux or severe ‘heartburn’, they should inform their GP as this could be a side-effect of the medication.
One of the other main side-effects to this medication is a condition called osteonecrosis of the jaw (this has been reported more in patients receiving intravenous bisphosphonates, than oral forms, which it is rare). It is advisable to seek a dentist before starting bisphosphonates for any remedial work (i.e. extractions), as this drug can cause delay in healing of the socket once the tooth is removed. It is also advisable to continue adequate oral hygiene during and after treatment with bisphosphonates.
There are some other alternative medicines to bisphosphonates for patients who are intolerant, and these should again be discussed further with a GP, or health professional.
I heard that some people can have Hormone replacement therapy (HRT) to address their risk of osteoporosis, is this still acceptable?
It is true that HRT does assist in bone protection as it replaces the oestrogen, when the levels drop at menopause; however, it has been decided that it is not safe to use this therapy as a means of prevention for osteoporosis, as it carries its own risks.
A large trial published in the Journal of the American Medical Association (JAMA) in 2002 demonstrated an increase risk of heart disease and breast cancer with prolonged HRT, thus it is something that needs careful consideration when starting for symptomatic menopause, and not osteoporotic protection.
Where can I find more information on this topic?
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