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Osteoporosis

Osteoporosis is a condition that affects the bones, causing them to become thin and weak.
Brought to you by NHS Choices

Introduction

Approximately three million people in the UK have osteoporosis, and there are over 230,000 fractures every year as a result.

Osteoporosis happens more commonly in old age when the body becomes less able to replace worn-out bone. Special cells within the bones, called living bone cells, are no longer able to break down old bone and renew it with healthy, dense new bone.

As you get older, you also lose a certain amount of bone, causing the bones to become thinner. The bones become fragile and more likely to break (fracture), particularly the bones of the spine, wrist and hips.

Bone is a living tissue that is constantly repairing itself. It is made of a hard outer shell, which contains a mesh of collagen (tough elastic fibres), minerals, blood vessels and bone marrow. This mesh looks a bit like a honeycomb, with spaces between the different parts. Healthy bones are very dense, and the spaces within bones are small. In bone affected by osteoporosis, the spaces are larger, making the bones weaker and less elastic.

Bones are repaired and reinforced by a range of proteins and minerals, which are absorbed from the bloodstream. They include calcium, phosphorus, proteins and amino acids. The growth of sex hormones controls the amount of mineral substance deposited in the bones. Changes in hormone levels can therefore affect the strength of the bones. For example, the female hormone oestrogen offers some protection against osteoporosis. After the menopause, oestrogen levels fall, often causing the bones to thin quickly.

Fast facts

  • Approximately three million people in the UK have osteoporosis.
  • It’s responsible for 200,000 fractures every year.
  • Osteoporosis affects about 20% of women aged 60-69.
  • Broken wrists, hips and spinal bones are the most common fractures in people with osteoporosis.
  • Of the 60,000 people who suffer osteoporotic hip fractures each year, 15-20% will die within a year from causes related to the fracture.

Symptoms

Osteoporosis is a condition that develops slowly over several years. The symptoms are not obvious in the early stages of the condition and can take months or years to appear. The early warning signs of osteoporosis can include joint pains and having difficulty standing or sitting up straight. You may have no warning before a minor fall or sudden impact causes a bone fracture.

When the bones are significantly thinned (a low bone mass), breakages of the wrist, hip or spinal bones (vertebrae) are most common. A cough or a sneeze may cause the fracture of a rib, or the partial collapse of one of the bones of the spine.

A fractured bone in an older person can be serious because the bone is no longer able to repair itself effectively. This can lead to arthritis and even disability, such as long-term problems with mobility. Some older people may be unable to live independently following an injury.

The characteristic stooping (bent forward) position that is common in older people is a visible sign of osteoporosis. It happens when the bones in the spine are fractured (cracked), making it difficult to support the weight of the body.

Is osteoporosis painful?

Osteoporosis usually doesn’t cause pain unless a bone is broken as a result of the condition. Although not always painful, spinal fractures are the most common cause of chronic pain associated with the condition. 

Causes

Bones are at their thickest and strongest in early adult life. From around the age of 35, more bone cells are lost than are replaced. This causes the bone to become thinner and weaker. People who exercise when they are young and who remain active into old age are less likely to get osteoporosis. This is because bones stay strong if they are used.

Women

Women are at greater risk of developing osteoporosis than men. This is due to the decrease in the hormone oestrogen after the menopause, which is essential for healthy bones. Women are at greater risk of developing osteoporosis when they have:

  • an early menopause (before the age of 45),
  • a hysterectomy before the age of 45, particularly when the ovaries are also removed, or
  • when their periods are absent for a long time (more than six months) as a result of over-exercising or over-dieting.

The male hormone testosterone also helps to keep the bones healthy. Men continue to produce this hormone into old age, but the risk of osteoporosis is increased in individuals with low levels of testosterone.

Diseases of the hormone-producing glands

Diseases of the hormone-producing glands may cause osteoporosis. The female hormone oestrogen and male hormone testosterone play an important role in keeping bones strong, by processing minerals such as calcium. Osteoporosis can be triggered by hormone-related diseases, including:

  • hyperthyroidism (overactive thyroid gland),
  • disorders of the adrenal glands, such as Cushing’s syndrome,
  • reduced output of sex hormones (oestrogen and testosterone),
  • disorders of the pituitary gland, and
  • diabetes.

Other factors

Other factors that can increase the risk of osteoporosis include:

  • a close family history of osteoporosis,
  • long periods of inactivity, such as long-term bed rest,
  • heavy drinking and smoking,
  • malabsorbtion problems, as experienced in coeliac disease and Crohn’s disease,
  • long-term use of high-dose corticosteroid treatment (widely used for conditions such as arthritis and asthma), which can affect bone strength,
  • long-term use of a medicine known as enoxaparin, which is used to prevent blood clots,
  • inadequate amounts of calcium,
  • low vitamin D levels, and
  • very low body mass (for example being very underweight - having a BMI of 19 or less - or having thin bones as a result of an eating disorder).

Diagnosis

Osteoporosis is not often diagnosed until the weakening of the bones has led to a broken bone. An X-ray cannot reliably measure bone density but is useful to identify spinal fractures.

DEXA scan

A bone density scan, called a dual energy X-ray absorptiometry (DEXA) scan, measures the density of bones and compares this to a normal range.

The difference between your bone density and this average is calculated and you are given what is called a ‘T score’. If your T score is between 0 and 1, you’re considered to be within the normal range. If it is between -1 and -2.5, you will be diagnosed with osteopenia, which is the name for the category of bone density between normal and osteoporosis.

You will be classed as having osteoporosis if your T score is below -2.5.

This test helps to measure the strength of bones and the risk of fracture.

Go to our topic on DEXA scans for more information.

Don’t panic if you’re diagnosed with low bone density

Although this is a useful warning, it may not necessarily mean you’re at high risk of fracture. Talk to your doctor about all your risk factors for osteoporosis and broken bones. This will help you take positive steps to improve your bone health.

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