Osteoporosis: definition, identification and prevention

Osteoporosis is a condition that weakens bones, making them fragile and prone to break and it affects more than three million people in the UK. It is identified by measuring bone mineral density (BMD), as low bone density means that bones may have lost strength. Bone density is assessed by Dual Energy X-ray (DXA) scanning, usually at the lower back (lumbar spine) and/or the hip. It is interesting to note that bone density is as strong a risk factor for excess fracture risk, as high blood pressure is for future stroke and high cholesterol is for a heart attack.

At least one in 3 women and 1 in 5 men over the age of 50 will sustain a fracture in their remaining lifetime that could be related to osteoporosis The most common sites of fracture are the wrist (Colles fracture), the shoulder, the vertebrae (small bones of the spine)  and the hip but really almost any bone fracture can be related to osteoporosis perhaps with the exception of the skull, fingers and toes!

 

Calculating the risk of fracture is based on a combination of clinical risk factors and bone density measurement. There are two different online clinical risk factor calculators which work out an individual’s 10-year risk of major osteoporotic fracture and hip fracture alone and both have been “approved” by the National Institute of Health and Care Excellence (NICE). These are:
 
Q-Fracture  - this has the advantage of including many clinical risk factors but has the disadvantage of not linking to BMD.
 
FRAX - this has far fewer risk factors but crucially allows inclusion of BMD of the hip. It also links directly to the National Osteoporosis Guideline Group (NOGG) recommendations of thresholds for BMD measurement and treatment.

 

Any male or female over the age of 40 years with clinical risk factors will benefit from a risk assessment using the risk calculators. The risk factors for both men and women include:

 

Family history of osteoporosis or fractures	Early menopause
Previous fracture over the age of 40 years	High alcohol intake
Overactive thyroid or parathyroid glands	Smokers
Eating disoprders especially anorexia nervosa	Chronic liver or kidney disease
Limited mobility due to neurological disease	Frequent fallers
Coeliac Disease or poor absorption of food	Chronic steroid (glucocorticoid) user
Rheumatoid arthritis	Ankylosing spondylitis

 

Active weight bearing exercise, good healthy nutrition and access to adequate reserves of Vitamin D (derived from sunlight, the diet or a supplement) is very important for maintaining good bone health. Gauging the right level of sunlight exposure so as to maintain good vitamin D levels without excess risk of skin cancer is problematic. Guidelines published by the Scientific Advisory Committee on Nutrition (SACN) recommend a Reference Nutrition Intake (RNI) for vitamin D of 10 μg/d (400 IU/d) for everyone in the UK aged 4 years and above. In practice this will mean that many adults will need to take a 400 iu vitamin D supplement.  
 
It would be ideal if improving lifestyle factors alone could reduce fractures but for those people with significant increased risk of fractures, especially in those diagnosed with osteoporosis by DXA scan, drug therapy will usually be advised. Unfortunately calcium supplements (with or without vitamin D)  are not sufficient and there is increasing anxiety that higher doses of calcium may be associated with increased risk of cardiovascular events such as a heart attack and stroke. While this risk is not proven preventative therapy with calcium and vitamin D alone in women around the time of the menopause is not recommended and other approaches are preferable.

One of the most effective ways of preventing and even treating low bone density is by taking hormone replacement therapy (HRT). There is good evidence that oestrogen is protective of the bones as well as the intervertebral discs, which are crucial for cushioning the vertebral bones and preventing crush fractures. There has been much debate regarding the safety of HRT, but the evidence is clear that if started around the time of the menopause, it can ensure good long term bone health as well as having many other positive effects such as treating hot flushes, sweats, low mood, low energy and vaginal dryness. HRT can be taken in many different forms such as gels, patches and tablets. The exact type is tailored to each woman’s needs to provide a completely integrated treatment.