Osteoporosis is a bone disorder caused by loss of bone mass, resulting in abnormal bone structure and an increased risk of fracture.

What is osteoporosis?

Computer artwork of a human female skeleton degenerating due to osteoporosis. At left is a normal skeleton. The degeneration, seen from left to right over time, is the loss of height and the backwards curvature of the spine.

Computer artwork of a human female skeleton degenerating due to osteoporosis. At left is a normal skeleton. The degeneration, seen from left to right over time, is the loss of height and the backwards curvature of the spine.

Osteoporosis is a bone thinning disease caused by loss of bone mass, resulting in weaker bones with abnormal  structure and an increased risk of fracture. 

Osteoporosis is a reduction in the amount of bone in the skeleton, making it less dense. This  decreases the strength of the bones and makes them more likely to break (fracture). The commonest fractures observed in osteoporosis  happen in the  spine, hips and wrists. Osteoporosis is the commonest acquired bone disorder and an important cause of fractures in adults. One in two women and one in five men over the age of 50 will have a fracture due to osteoporosis. 

What causes osteoporosis? 

Bone is a living tissue that is constantly breaking down and  rebuilding its structure   through a lifelong process known as remodelling. Some  cells in the bone called osteoclasts break down old, damaged bone to make way for new, healthy bone that is laid down by another type of  cells called osteoblasts.  Approximately 10% of the normal bone is replaced in this way every year, and the amount of bone removed is balanced by the amount of new bone laid down. With older age, and after the menopause in women, the remodelling process goes too quickly, and becomes unbalanced so that more bone is broken down than can be replaced. 

Osteoporosis is more common  in women and older people, however men and younger people can also be affected.  Most of the time, there is no specific cause behind osteoporosis (primary osteoporosis) although, in some occasions , there might  be reasons behind it (secondary osteoporosis). Some conditions and medications that  can increase the risk of osteoporosis are:

  1. Hormone abnormalities.
  • Oestrogen deficiency in women. This is usually the result of menopause in women, although there are other conditions in younger women that can also lower oestrogen levels. This is one of the reasons why osteoporosis is more frequent in women.
  • Overactive thyroid (hyperthyroidism)
  • High levels of parathyroid hormone (primary hyperparathyroidism)
  • Excess cortisol production (Cushing’s syndrome)
  • Low levels of testosterone in men (hypogonadism).
  1. Other causes include: 
  • inflammatory arthritis (especially rheumatoid arthritis).
  • inflammatory bowel disease
  • coeliac disease
  • chronic kidney disease.
  1. Medications such as: : 
  • steroids (like prednisolone or anabolic steroids)
  • some anti-epileptic drugs
  • anti-oestrogen treatment for breast cancer (such as aromatase inhibitors)
  • testosterone-lowering treatments for prostate cancer.

Some lifestyle factors  can also affect the risk of developing osteoporosis. For example, smoking, drinking excessive alcohol and not exercising increase the risk of developing osteoporosis, as does being underweight.

Regular exercise and a healthy diet  are ways of reducing the risk of developing osteoporosis. Calcium makes bones strong and most adults need approximately 700mg of calcium a day; this can be achieved by eating low fat dairy food every day (two to three portions) or by adding  bread and cereals, certain fish (sardines, pilchards, crab and salmon for example) and vegetables (broccoli and oranges) to the diet. There are some dairy free alternatives enriched with calcium that people unable to eat diary can incorporate in their diets too. Vitamin D is also important for bone strength – it is manufactured by the skin when exposed to sunlight and this provides approximately 90% of our vitamin D. The remaining 10% of vitamin D is obtained from the diet. Many people in UK have Vitamin D deficiency, especially in winter, due to the limited sun exposure. In 2016 the UK government recommended that most people should take a vitamin D supplement in the winter, and some people should take it all year round. 

What are the signs and symptoms of osteoporosis? 

Osteoporosis has no symptoms (asymptomatic) until fractures occur. Any fracture that occurs following minor injury should raise suspicion of underlying osteoporosis. The most common fractures  seen  in osteoporosis are those of the hip, wrist and spine bones (vertebrae), although fractures can occur at any site. Usually, fractures of the hip and wrist occur after a fall, but fractures of the vertebrae may  happen without any obvious injury. Such fractures may not cause any symptoms or may be accompanied by the development of acute back pain,  that may disappear over weeks or months. Multiple fractures of the spine can cause loss of height and significant spinal deformities especially marked abnormal curvature of the spine (kyphoscoliosis). 

How common is osteoporosis? 

About half of women and one in five men over the age of 50 will have a fracture from osteoporosis at some point in their lifetime. Vertebral and hip fractures are the most commonly encountered. However, although the chances of having a hip fracture increase as age advances, only about 0.3–0.5% of women over the age of 75 will suffer from a hip fracture. This increases to about 1% of women over the age of 85. More women than men tend to have fractures of the hip. 

Is osteoporosis inherited? 

There is a tendency for osteoporosis to run in families, but the inheritance of a specific gene or genes has not yet been identified. This means individuals may inherit a greater likelihood of developing osteoporosis, but if one of the parents is affected, it does not necessarily mean that the children will develop the condition.  

How is osteoporosis diagnosed? 

Diagnosis of osteoporosis is usually made by measuring bone density with a dual energy X-ray absorptiometry scan (DEXA scan) and, routinely, this will be done on the hips and vertebrae (back bones) although the wrists can also be scanned. In severe osteoporosis, thin bones or vertebral fractures may be seen on simple X-rays.    

Blood tests may also be carried out to check for other causes of osteoporosis and these may include measurement of calcium, thyroid and parathyroid hormone levels. 

How is osteoporosis treated? 

Exercise is important in building bones, making it important for all patients with osteoporosis to have regular exercise, particularly weight bearing and resistance exercise. Patients should also try to maintain a healthy lifestyle and diet. Alcohol and smoking are also risk factors for osteoporosis and their use should be discouraged.

The major class of drugs used to treat osteoporosis is called bisphosphonates. These drugs stick to the surface of bones, where they can enter bone cells and prevent the osteoclasts from breaking bone down, hence preventing bone loss and keeping the remodelling process in balance. They have been shown to reduce the risk of hip and vertebral fractures.

The most commonly used bisphosphonates are risedronate and alendronate, which are normally taken orally once weekly. Zoledronic acid may also be used and is given as a once-yearly infusion. Vitamin D and calcium should be replaced in all patients starting treatment for osteoporosis to make the treatment as effective as possible. 

Oestrogens (i.e. hormone replacement therapy, HRT) can also be given to treat postmenopausal osteoporosis; however, it is important that women discuss the potential risks of HRT with their doctor before starting HRT. individual women to decide if treatment should be continued. Oestrogens are particularly useful in preventing osteoporosis women who develop premature menopause (before the age of 40 years).

Some alternative treatments are available for those patients who cannot take bisphosphonates, or for those who do not show a good response to them. These available medications include denosumab (injected every six months), teriparatide (injected every day for two years) and raloxifene (taken by mouth). 

Are there any side-effects to the treatment? 

The side-effects of taking bisphosphonates, can include indigestion, a change in bowel habits (constipation or diarrhoea), tiredness, dizziness or headaches, aches and pains, swelling of the legs, feeling sick and  flu-like symptoms.      

In patients treated with bisphosphonates for a longer time, there are other possible side effects (osteonecrosis of the jaw and atypical femoral fractures), but these are very rare. Hence, it is important to have a dental check-up (and any required dental procedures) before or as soon as possible after starting treatment with bisphosphonates. If you are having treatment with bisphosphonates and you get hip, thigh or groin pain, you should see your doctor because you may need an X-ray to check for atypical fractures. 

What are the longer-term implications of osteoporosis? 

The long-term implications of osteoporosis are the increased risk of fractures from minor injury. Immobility caused through these fractures can also have long-term consequences because it reduces physical ability, particularly in the elderly. Maintaining a healthy lifestyle and diet, undertaking regular exercise, and minimising alcohol and smoking exposure are the most important steps to preventing osteoporosis.


Last reviewed: Jan 2019