Paget's disease of bone disrupts the normal cycle of bone renewal, causing bones to become weakened and possibly deformed.

It's a fairly common condition in the UK, particularly in older people. It's rare in people under 50 years of age.

There are treatments that can help keep it under control for many years, but it can cause persistent pain and a range of other problems in some people.

Paget's disease of bone can affect 1 bone or several bones. Commonly affected areas include the pelvis, spine and skull.

Symptoms can include:

• bone or joint pain
• skin feeling warm over the affected bone
• changes in bone shape
• a shooting pain that travels along or across the body, numbness and tingling (peripheral neuropathy), or balance problems

But in many cases there are no symptoms and the condition is only found during tests carried out for another reason.

Read more about the symptoms of Paget's disease of bone.

See your GP if you have:

• persistent bone or joint pain
• deformities in any of your bones
• symptoms of a nerve problem, such as numbness, tingling or balance problems

Your GP can organise tests to check your bones and look for problems such as Paget's disease of bone.

Read more about how Paget's disease of bone is diagnosed.

Bone cells regenerate in a similar way to skin – old bone is removed and replaced by new bone. This is known as bone remodelling.

2 cells are responsible for this:

• osteoclasts – cells that absorb old bone
• osteoblasts – cells that make new bone

In Paget's disease of bone, something goes wrong with the osteoclast cells and they start to absorb bone at a much faster rate than usual.

The osteoblasts then try to produce new bone more quickly, but the new bone is larger and weaker than normal.

It's not clear what triggers this, but you're at a higher risk if you have a family history of Paget's disease of bone. You may inherit a genetic fault that means you're much more likely to develop the condition.

There's currently no cure for Paget's disease of bone, but treatment can help relieve the symptoms.

If you do not have any symptoms, your doctor may suggest keeping an eye on your condition and delaying treatment until any problems occur.

The main treatments are:

• bisphosphonate medication – medicines that help control bone regeneration and are used to control pain
• supportive therapies – including physiotherapy, occupational therapy and devices such as walking sticks or shoe inserts
• surgery – this may be needed if further problems develop, such as fractures, deformities or severe joint damage

Ensuring you get enough calcium and vitamin D can also help. Some people may need to take supplements.

Read more about how Paget's disease of bone is treated.

Paget's disease of bone can sometimes lead to further, potentially serious problems.

These include:

• fragile bones that break more easily than normal
• osteoarthritis, which causes painful and stiff joints
• enlarged or misshapen bones
• permanent hearing loss (if the skull is affected)
• heart problems
• in rare cases, bone cancer

Read more about possible complications of Paget's disease of bone.

There are several other types of Paget's disease that are not related to Paget's disease of bone.

These include:

• Paget's disease of the nipple or breast – a rare type of breast cancer
• Paget's disease of the penis – a rare type of penile cancer
• Paget's disease of the vulva – a rare type of vulval cancer

The general term "Paget's disease" is sometimes used to refer to Paget's disease of bone.