Osteoporosis

What is Osteoporosis?

Osteoporosis is a marked loss of bone mineral density (BMD) that as measured on a bone density scan. Just like high blood pressure means hypertension, so a low BMD means osteoporosis. The underlying issue is loss of mineral from the bones (mainly calcium).

A fall from standing height that results in a fractured bone is called a Fragility Fracture and osteoporosis is a very important cause of Fragility Fractures.

Why is Osteoporosis important?

Over half of women over 50 years, and around a third of men over 60 years, will one day get a fragility fracture. Common fragility fractures are vertebral crush (wedge) fracture and radial fracture (Colles).

Around 20% of fragility fractures are at the hip. These fractures at the neck of femur are a major issue in older people with osteoporosis, and a common trigger for a major health deterioration. Around a fifth of (mainly women) who get a fractured hip need long term care.

How is Osteoporosis Diagnosed?

Osteoporosis is diagnosed in two different ways

• Most commonly, from a bone density scan (Bone Densitometry).
• On occasion, when a fragility fracture has already occurred.

The Bone density is most often measured in the spine and the hip. There are two scores in the report:

• The Z score: This is the bone density compared with someone of the same age and sex.
• The T Score: This is the bone density compared with a young (age 20 to 30) healthy person, also of the same sex.

Osteoporosis has traditionally been defined as a T score is -2.5 or lower. The lower (more negative) the T score, the more severe the osteoporosis eg. a T score -3.5 indicates severe osteoporosis.

Osteoporosis is ultimately a condition that can only be diagnosed with 100% certainty by a pathologist. But none of us want bone biopsies and such direct measures of bone architecture are not very useful! The DEXA scan is the best non-invasive way of looking for osteoporosis.  However, the -2.5 cut-off is arbitrary and most fragility fractures occur with a T score better than -2.5 (in the “osteopenia” range).

The Z score is not looked at as much but also important. The Z score of -2 or more indicates that the bone density is significantly lower than someone of the same age and sex, and there may be an underlying cause.

What are the causes of Osteoporosis?

Osteoporosis is usually Primary (no underlying medical disease) and reflects a more marked loss of bone density with age.

These are the following risk factors for osteoporosis:

• Increasing Age
• Female Sex
• Smoking

Low Body Mass Index (under 18.5)
Family history of fragility fracture

• Sedentary lifestyle over a long time.
• Vitamin D deficiency.
• High Alcohol Intake (eg. more than 14 units/week for females and 21 units/week for males).

Osteoporosis may also be Secondary to an underlying cause:

• Premature (Under 40) or Early (under 45) menopause.
• Chronic Kidney Disease or Chronic Liver Disease.
• Long Term oral steroid medication (6 months or longer).
• Rheumatoid Arthritis.
• Malabsorption (eg. poorly controlled Coeliac Disease, Crohns Disease).
• Overactive Thyroid (Hyperthyroidism), Overactive Parathyroid (Hyperparathyroidism).
• Low Sex Hormones (Hypogonadism eg. Klinefelter syndrome).
• Cushing Syndrome (Very Rare).

There is a medicare rebate for Bone Densitometry Testing when the osteoporosis risk is significant – and this includes the above list of secondary causes.

What can I do for Osteoporosis or Osteopenia?

There are things you can do yourself to increase bone density:

• Exercise: resistance and weight-bearing exercises are best
• Give up smoking
• Adequate dietary calcium
• Adequate Sunlight (Vitamin D)
• Falls Prevention is also important in people at risk of falls.

Does Osteoporosis need treating?

It takes both osteoporosis and of course a fall to cause a fragility fracture. Therefore, osteoporosis in someone at risk of falls is much more of a risk than osteoporosis in an otherwise fit and healthy person. So what matters is the risk of fracture. Clearly, that risk includes bone mineral density but there are lots of other factors that increase fracture risk.

You can use the following self-test to indicate your risk of a fragility fracture in the next 10 years: Qfracture. This self-test may be taken with or without BMD measurements.

There is a difference between Guidelines around the world in terms of the thresholds set for treatment. These thresholds are dependent on an analysis of cost effectiveness.

The Australian national osteoporosis guideline is simpler in generally recommending treatment if the BMD T score is lower than than -2.5.

What are the treatment options?

These are the main treatment options that are all available through your GP

• Bisphosphonates
•  eg. Alendronate tablet (brand ®Fosamax), and risedronate (brand ®Actonel) : These are taken daily, weekly or monthly and increase the bone density substantially.
• There’s a once yearly infusion for severe cases.
• Denosumab (eg. Prolia® injection every 6 months).
• Raloxifene (tablet) (an analogue of Oestrogen).
• HRT (only works whilst the HRT is taken, not the first line treatment for osteoporosis).
• ®Strontium (tablet) is also an option.
• Parathyroid hormone eg. Teriparatide (injection) – typically an 18 month course of daily subcutaneous injections for severe osteoporosis.

The most common first line treatments are bisphosphonate tablets or The 6-monthly Denosumab injection. Medicare fund all of the above when any Pharmaceutical benefit scheme restrictions are met. The medicare restrictions for Teriparatide daily injections are strict because of the expense & it reserved for severe osteoporosis where other treatments have not worked.

When considering what therapy to go for, remember that only one outcome really matters: The rate of fragility fracture. What really matters is that the bones are able to withstand a slipping over on the pavement. Reducing the risk of hip fractures is the most important outcome for most people, although medication has the greatest effect on reducing vertebral fractures. The common first line treatments have good evidence for a reduction in hip fracture and the risk of side effects are generally low.

Oral Calcium with Vitamin D is also additionally recommended in the elderly, and may also be recommended in post menopausal females with osteoporosis. In addition, the Bisophosphate trials & Prolia generally included calcium /vitamin D taken with the Bisphosphonate, so it’s usually suggested that both are taken.

Note that there is a slight caution with oral Calcium tablets in that there is a small risk of high calcium levels in both the blood and urine. High calcium in the urine could predispose to kidney stones – particularly in the 1 in 20 people who are already high urinary calcium.

The medicare prescribing rebate has a different threshold which is higher in terms of T score and age. The rebate is not generally an issue for oral medication because the private cost is generally under the rebate threshold. The private costs of injections can, however, be high, and medicare is significantly more restrictive than the guideline recommendations.

Tell me more about The Bisophosphonates

The Bisophosphonates prevent the active absorption of bone by the bone-aborbing cells (Osteoclasts). They have been around a long time and the evidence for them reducing rates of fracture is very strong.

The tablets should be taken in the correct way to prevent irritation of the upper Gastrointestinal Tract such as heartburn. The Bisphosophonate tablet should be taken:

• First thing in the morning on an empty stomach with a large glass of water.
• You should be sitting upright or standing when you take the tablet and must not lie down for at least 30 minutes afterwards (or 60 minutes if you’re taking ibandronate).
• No food, drink or other tablets should be taken during this time (one brand is available that does allow it to be taken with breakfast).

In the bisphosphonate trials, Over a three year period without treatment around 15% got a vertebral fracture – reduced to 8% vertebral fracture rate with Treatment. Similarly, 2% got a hip fracture over 3 years without treatment – reduced to 1% with treatment. So the medication roughly halves the rates of fracture.

People often are aware of these risks of Bisphosphonates though risks are very low:

•  Osteonecrosis of the jaw : The risk is less than 1 in 10,000 per year. Mostly occurs in people who have the medication injected into a vein for prevention of bone complications in people undergoing treatment for cancer. This is an overstated risk on the internet but it can happen. Therefore, guidelines suggest that you see a dentist before starting the medication and let the dentist know that you are going to start a “bisphosphonate.” The risks are increased by poor oral health, undergoing dental extraction, diabetes and oral steroid use. You should know about it, mention it to the dentist on each visit, and don’t worry.
• Atypical hip fracture: These are unusual types of hip fracture and again rare with a treatment risk of around 0.5 to 1 per 1,000 per year. The risk is highest in women on long term treatment (more than 5 years).

Bisphosphonates roughly halve the fracture rate so the benefit in general would vastly outweigh these risks.

What monitoring is recommended?

The Australian national osteoporosis guideline states that “in patients with confirmed osteoporosis, repeat bone mineral testing is not generally required, however it may be conducted before initiating a change in, or cessation of, anti-osteoporosis therapy.”

Once Osteoporosis has developed and the person is on treatment (anyway) then there’s not usually much to be gained by repeating the test unless the treatment is going to be stopped. Bisphosphonate therapy is often recommended initially for 3-5 years. At that point, it may be worth repeating the BMD.

It is useful to monitor BMD in someone who has Osteopenia – to help inform the decision if and when to start anti-osteoporosis medication. A gap of at least 2 years between measurements is usually recommended.

Monitoring should ideally be done by the same type of scanner.  There is  degree of error expected in the measurements, but A change of 5% or more might be significant.

Should I see a GP or an endocrinologist?

Most people with osteoporosis can be managed very well by a GP who has access to all the major clinical resources. The GP will consider secondary causes of osteoporosis and arrange blood tests as required. When a secondary cause such as hyperparathyroidism is identified then your GP will refer you to an endocrinologist.