What is Paget's disease?
Paget's disease disrupts the normal cycle of bone renewal and repair, causing bones to become weakened and deformed.
Bone pain is the most common symptom of Paget's disease, often affecting the pelvis or spine. The pain is usually worse when lying down.
You should visit your doctor if you experience bone pain or notice any bone deformities.
However, in many cases of Paget's disease there are no noticeable symptoms, and it is only diagnosed during tests for an unrelated medical condition or when a bone is fractured.
Why does Paget's disease happen?
Paget's disease is caused by a problem with the process of bone renewal that results in bone being replaced at a faster rate than usual. This leads to enlarged bones that are weak and brittle.
It is not clear why this happens, but both genetic and environmental factors are believed to be important. In around 15% of cases there is a family history of the condition.
Read more about the causes of Paget's disease.
Treating Paget's disease
The condition is not usually treated immediately if Paget's disease is not causing any symptoms, although your health will be regularly monitored.
There is no cure for Paget's disease. Treatment can help relieve symptoms and prevent the condition getting worse.
Medication can help control bone regeneration, with a type of medicine called bisphosphonates being the first choice. These are taken as a tablet or injection.
Over-the-counter painkillers such as paracetamol and ibuprofen can relieve pain.
Surgery is only used if Paget's disease causes further problems, such as osteoarthritis or a bone fracture.
Read more about treating Paget's disease.
Complications of Paget's disease are uncommon, but can be potentially serious. They include bone deformities, hearing loss and osteoarthritis.
Read more about complications of Paget's disease.
Who is affected?
The UK has the highest rates of Paget's disease in the world and it is relatively common in countries where there have been high levels of migration from Britain, such as Australia, New Zealand and South Africa.
It most often occurs in people of white British descent and is very rare among other ethnic groups.
Paget's disease is also an age-related condition, rarely affecting young people.
Symptoms of Paget's disease
Many people may not be aware they have Paget's disease, as it often has no symptoms. If you do experience symptoms, the most common sign is bone pain.
Paget's disease usually affects the bones of the pelvis or spine. Other areas of the body that can be affected include the skull, shoulders and the long bones in the arms and legs, particularly the thigh bone.
In two out of every three cases of Paget's disease, more than one bone is affected.
Bone pain caused by Paget's disease has been described as a constant, dull pain deep within the affected part of the body. The pain is usually worse at night when you are lying down. The affected area may also feel warm.
As Paget's disease progresses, you may experience deformities in the affected bones, such as twisted or misshapen limbs or scoliosis (curvature of the spine). Affected bones can sometimes fracture (break), particularly the longer bones in your arms and legs.
Symptoms of fractured bones include:
- pain and swelling in the affected area
- bruising or discoloured skin around the bone or joint
- the limb or body part being bent at an unusual angle (angulation)
Paget's disease can cause a range of other symptoms depending on which bones are affected by the condition. These are described below.
If Paget's disease develops inside the bones of your skull it can cause the following symptoms:
- hearing loss – which can be total or partial
- vertigo – feeling very dizzy or the sensation you are moving when standing still
- tinnitus – a constant buzzing or ringing noise in your ears
Abnormal bone growth can cause damage to nearby cartilage. Cartilage is the thick, spongy tissue that cushions your joints. Cartilage damage can lead to progressive joint damage, known as osteoarthritis.
Symptoms of osteoarthritis include:
- stiffness – usually worse when you wake up in the morning, but often improves within about 30 minutes of starting to move
- difficulty moving your affected joints
Many of the major nerves in your body run through, or alongside, your bones. Abnormal bone growth can result in a bone compressing (squeezing) or damaging a nerve.
Depending on which nerve is affected, this can lead to a wide range of symptoms. Possible symptoms affecting the nerves (neurological symptoms) include:
- pain that travels from the base of your spine down into your legs (sciatica)
- pain that travels from your neck into your arms and chest (cervical radiculopathy)
- numbness or tingling in the affected limbs (peripheral neuropathy)
- partial loss of movement in your limbs
- loss of balance
- bowel incontinence or urinary incontinence (the loss of bowel or bladder control)
When to seek medical advice
You should always visit your doctor if you:
- have persistent bone pain
- notice deformities in any of your bones
- experience any neurological symptoms, such as numbness or tingling
Paget's disease causes
Paget's disease is caused by abnormal bone regeneration, although it is not clear exactly why this happens.
To understand how Paget's disease affects your bones, it is useful to understand how they are kept healthy throughout life.
It is often assumed that once a person's bones reach adult size, they do not change, but this is not the case.
In a similar way to skin, bone cells undergo a continuous cycle of regeneration, where old bone is removed and is replaced by new bone. This cycle is known as bone remodelling.
Bone is made up of a protein called collagen and a mineral called hydroxyapatite. Two specialised cells are responsible for bone renewal and repair. These are known as:
- osteoclasts – cells that absorb old bones
- osteoblasts – cells that make new bone
In Paget's disease, something goes wrong with the osteoclast cells and they begin to absorb collagen at a much faster rate than normal. The osteoblasts attempt to compensate for this by producing new bone, but because they have to work at a faster speed than normal, the bone that they produce becomes weak and unstable.
Over time, this disruption to the bone remodelling process can lead to bones becoming bigger and weaker than normal.
Possible causes of Paget's disease
The exact cause of Paget's disease is unknown, but it is likely the condition develops as a result of a combination of genetic and environmental factors.
These are described below.
People who inherit certain mutated genes from their parents have an increased chance of developing Paget's disease.
The most important of these is a gene called SQSTM1. People with a mutation in this gene have a greatly increased risk of developing Paget's disease in later life. Seven other genes have now been identified that also increase the risk of Paget's disease substantially.
In about 15% of cases, Paget's disease runs in families. If you have a close relative with Paget's disease, such as a parent, brother or sister, you are seven to eight times more likely to develop the condition.
The fact that the number of people affected by the disease has fallen sharply over the last 50 years in the UK, while in contrast the number of people affected in other countries has remained static, indicates that environmental factors may play a role.
The severity of symptoms also seems to be decreasing. Up to 60 years ago it was not uncommon for people to experience severe symptoms in multiple bones, but this is no longer the case.
The reasons for these differences are unclear.
One theory is that Paget's disease might be caused by a slow-acting viral infection. Possible triggers include:
- measles virus
- canine distemper virus – responsible for a type of viral infection that affects animals, mainly dogs (distemper)
- respiratory syncytial virus (RSV) – which causes respiratory infections during childhood
Due to vaccines, both measles and distemper are now uncommon infections. This could account for the decrease in cases of Paget's disease.
Another theory suggests people with rural lifestyles may be at increased risk of developing Paget's disease. As the number of people living this type of lifestyle is much less common than it was, it could offer an alternative explanation for the fall in cases of Paget's disease.
Improvements in nutrition and a reduction in cases of rickets over the past 50 to 100 years have also been suggested as possibilities for the decreasing severity of Paget's disease.
Paget's disease diagnosis
As Paget's disease doesn't always cause symptoms, many cases are diagnosed during tests for another condition.
However, it is not yet known whether an early diagnosis is effective in preventing the most serious complications, such as hearing loss and bone deformity.
Alkaline phosphatase (ALP)
In many cases, Paget's disease is first diagnosed during a blood test for another, unrelated condition.
This is because the abnormal pattern of bone remodelling leads to a rise in levels of a chemical called alkaline phosphatase (ALP) in your blood that can de detected during a blood test.
ALP is sometimes called serum alkaline phosphatase (SAP) or bone-specific alkaline phosphatase (BSAP).
X-rays and bone scans
An X-ray can determine whether the bones have become enlarged. In some cases, the condition is diagnosed after an X-ray for another problem, such as a bone fracture.
A bone scan may also be recommended. A small amount of a harmless radioactive substance is injected into your blood, which collects in the areas of bone where there is the most activity, such as where there is abnormal bone remodelling.
A special camera, known as a gamma camera, is used to highlight where the radiation has collected.
Further testing is usually only required if:
- you develop abnormalities that affect one or more joints
- you are experiencing neurological symptoms (symptoms that affect your nerves, such as pain, numbness or tingling)
- a diagnosis of bone cancer is suspected (although this is very rare)
In these circumstances, tests that can be used are:
- a bone biopsy – where a sample of bone is removed under local or general anaesthetic so it can be studied in detail
- a computer tomography (CT) scan – where a series of X-rays of the affected bone are taken to show a detailed three-dimensional image
- a magnetic resonance imaging (MRI) scan – another type of scan that uses a strong magnetic field and radio waves to build up an image of the inside of the affected bone
Treatment for Paget's disease
Not everyone with Paget's disease will require treatment. If treatment is needed, medication is most often used.
If a blood test reveals you have Paget's disease but you are not experiencing symptoms, a policy of "watchful waiting" is likely to be recommended. This means you will not receive treatment immediately, but your progress will be carefully monitored using regular blood tests.
Treatment is usually recommended if you have symptoms such as bone pain or pain, numbness and tingling.
Treatment cannot cure Paget's disease, but it can relieve symptoms and prevent the condition from getting worse. Treatment also reduces your chances of developing any complications of Paget's disease.
Treatments for Paget's disease include:
- medication to help regulate bone remodelling
- medication to relieve pain
- physical therapy
Regulating bone remodelling
There are a number of different medications used to help regulate bone growth in cases of Paget's disease.
If you are being treated with one of these medicines, you may have regular blood tests or X-rays to check they are working.
Bisphosphonates are the first-choice treatment to regulate bone growth. They work by controlling the cells that absorb old bone (osteoclast cells), which means the bone regeneration process should return to normal.
A type of bisphosphonate called risedronate has proved to be effective in treating Paget's disease and is usually recommened. Risedronate is available in tablet form and most people are advised to take one tablet a day over the course of a two-month period.
Take your risedronate tablet while you are standing or sitting up and avoid lying down for at least 30 minutes after taking it. This will help prevent heartburn (burning chest pain and discomfort).
Side effects of risedronate include:
If you are unable to take risedronate because you are unable to stay upright for 30 minutes, there are alternative bisphosphonates, such as pamidronate. Pamidronate is given by injection, usually once a week over the course of six weeks.
The most common side effects of pamidronate include:
- mild, flu-like symptoms, such as a high temperature
- joint pain
However, these side effects usually pass within 48 hours of receiving an injection.
Zoledronic acid, also called zoledronate, is a newer type of bisphosphonate increasingly being used as an alternative to risedronate or pamidronate.
Zoledronic acid is given as an injection and its effects can last a long time. You may only need an injection once every two years.
Flu-like symptoms, such as chills, fever and joint pain, are common after receiving your first injection, although these side effects should pass within three to four days.
Calcitonin used to be a common treatment for Paget's disease, but is only used in certain circumstances now.
If you have low levels of calcium in your blood (hypocalcaemia), it is unsafe to take bisphosphonates safely because they can lower your calcium levels further.
In these circumstances, an alternative medication called calcitonin may be recommended. Calcitonin is a man-made version of a hormone known to prevent bone loss. It is given by injection once a day. The recommended course will depend on how well you respond to treatment, although it usually lasts between six and 18 months.
Common side effects of calcitonin include:
- changes in how things taste
- abdominal pain
In most cases, painkillers available over the counter, such as paracetamol or ibuprofen, should relieve the symptoms of bone pain. If your symptoms continue, your doctor can prescribe more powerful painkillers.
Some people with Paget's disease find they benefit from physiotherapy or occupational therapy, particularly those who have had fractures or other types of damage in the bones of their legs or spine.
There are devices designed to reduce the weight placed on affected bones, which should help reduce pain and make everyday physical activities easier. Examples include:
- walking devices – such as a cane or walking frame
- orthotics – insoles made of plastic that fit inside your shoe to help support your feet
- spine braces – designed to support the spine in the correct position
Some therapists also use different types of energy, such as electric currents or impulses, to stimulate the nervous system (energy-based therapy). The electric impulses are thought to ease pain and promote healing in some people.
The therapist will also be able to teach you a number of exercises that can:
- improve your muscle strength
- maintain the range of movement and flexibility in your joints
- increase your physical stamina
Surgery is usually only used if Paget's disease causes further problem, such as bone fractures.
If you develop a fracture, surgery may be required to realign the bones so the affected bone is able to heal properly.
If you experience severe osteoarthritis, surgery may be required to repair or replace a damaged joint. Surgical options for osteoarthritis include:
- an arthroplasty – where the damaged joint is removed and replaced with an artificial joint: the most commonly performed arthoplasties are hip replacements and knee replacements
- arthrodesis – where the joint is fused into a permanent position
Surgery may also be used if you develop bone deformities. A procedure called an osteotomy involves carefully cutting the affected bone so it can be straightened. This operation is usually carried out under general anaesthetic, so you will not experience any pain.
Complications of Paget's disease
Paget's disease can cause several further problems to develop, although these are usually rare.
The abnormally rapid process of bone regeneration (remodelling) associated with Paget's disease can sometimes lead to a build-up of calcium in the blood. The medical term for this is hypercalcaemia.
Hypercalcaemia only occurs in people with Paget's disease who have been confined to bed after having an operation or following a fracture. However, even in these circumstances, hypercalcaemia is quite rare.
Symptoms of hypercalcaemia include:
- extreme tiredness
- bone pain (or worsening bone pain if already present)
It is also relatively common for people with hypercalcaemia to develop kidney stones.
Hypercalcaemia can be treated using a combination of medications to lower blood calcium levels and slow down bone remodelling.
In severe cases of Paget's disease, the blood vessels inside the bones can become damaged. This means the heart has to work harder to pump blood around the body. Sometimes, the heart may no longer be able to pump enough blood around the body to meet demand. This is known as heart failure and is a very rare complication of Paget's disease.
Symptoms of heart failure include:
- breathlessness (dyspnoea) when you are more active than normal, or sometimes when you are resting
- extreme tiredness and weakness
- oedema – swelling in the legs, ankles and feet
Heart failure can be treated using a combination of medications designed to reduce strain on the heart while also helping it to work more efficiently. In some cases, surgery may be recommended to repair or replace a damaged heart valve.
Bone cancer can, in very rare cases, occur as a complication of Paget's disease. It is estimated fewer than one in 1,000 people with Paget's disease will go on to develop bone cancer later in life, usually many years after Paget's disease was first diagnosed.
Symptoms of bone cancer include:
- bone pain very similar to the pain associated with Paget's disease itself – a dull ache usually worse at night
- swelling around the affected bone
- a noticeable lump in the affected bone
Sarcoma is usually an aggressive type of cancer and it is often necessary to remove the affected bone to prevent the cancer spreading to other parts of the body.
The changes to your bones caused by Paget's disease can also cause other problems, depending on which bones are affected.
These problems may include:
For more detail about these, read about the symptoms of Paget's disease.