Paget's disease of bone

Also called Osteitis deformans

Bone remodelling gone wrong, making bone bigger but weaker. Usually silent, and found on an X-ray or a blood test done for something else.

What it is

A condition in which bone is broken down and rebuilt too fast, producing bone that is larger but structurally disorganised and weak.

It affects mainly people over 55 and is more common in the UK than almost anywhere. It usually affects one or a few bones: the pelvis, spine, skull, femur and tibia are the classic sites.

Most people have no symptoms. It is commonly found by accident, from a raised alkaline phosphatase on a blood test or a change seen on an X-ray taken for another reason.

When it does cause problems they follow the site: bone pain, deformity such as a bowed leg or an enlarging skull, osteoarthritis in the neighbouring joint, fractures through weakened bone, and, where the skull is involved, hearing loss from compression of the nerve.

Treatment with a bisphosphonate, usually a single intravenous infusion of zoledronic acid, controls the disease effectively and often for years.

Rarely, and importantly, Paget's bone can become a sarcoma. New, severe or changing pain in a previously affected bone is a warning sign that must not be dismissed as the Paget's getting worse.

Signs you might notice

Often none.

Deep, aching bone pain, often worse at night and at rest rather than on movement, which distinguishes it from arthritis.

Bone deformity: a bowing leg, an enlarging skull, a hat becoming tight.

Warmth over the affected bone.

Joint pain in a nearby joint.

Hearing loss, or headache, where the skull is involved.

Fracture after minor injury.

Urgent: new, severe or rapidly worsening pain in an affected bone, or a lump over it, which needs assessment for sarcoma.

Also: new neurological symptoms, weakness or numbness, where the spine is involved.

Ask about it in any older person with an unexplained isolated raised alkaline phosphatase and normal liver tests.

How it can affect day-to-day life

The night-time and rest pain pattern is what distinguishes it from arthritis, and it is worth describing precisely to a clinician, because the two are frequently confused and treated differently.

Once treated, alkaline phosphatase is used to monitor, and a rise years later suggests reactivation.

Hearing should be tested where the skull is affected, and hearing aids offered; the loss is often gradual and attributed to age.

Where a leg bone is affected and bowed, gait changes and secondary arthritis follow, and physiotherapy, footwear and walking aids all help.

Bisphosphonate treatment requires adequate calcium and vitamin D beforehand to avoid low calcium afterwards, and a dental check first because of the small risk of jaw problems.

Family members have a somewhat increased risk, and can have alkaline phosphatase checked if concerned.

Supporting someone well

Ask about it where alkaline phosphatase is raised with normal liver tests in an older person.

Describe the pain pattern precisely: night and rest pain points at bone rather than joint.

Ask for a bone scan to see which bones are involved.

Ask about a single zoledronic acid infusion; it is effective and often long-lasting.

Have calcium and vitamin D checked and corrected before treatment, and have a dental check.

Have hearing tested if the skull is involved, and ask for hearing aids.

Report new or worsening pain in an affected bone urgently rather than assuming progression.

Ask for physiotherapy and appropriate footwear where a leg is affected.

Where to get help

A GP practice for blood tests, X-rays and referral; rheumatology or a metabolic bone service for treatment.

Audiology where the skull is involved.

Royal Osteoporosis Society run a helpline and cover metabolic bone conditions.