Paget disease of bone !
A bone disease in which old bone is broken down and rebuilt too fast and in disorder, making bones large, weak and painful. Often found by chance.
Updated 2026-11-01
Structures involved
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Why it happens
What it is
A localised disorder of bone remodelling in which overactive osteoclasts are followed by disorganised new bone formation. The affected bones become enlarged, deformed and mechanically weak. It most often affects the pelvis, spine, skull, femur and tibia.
Who gets it
Mainly a disease of people over 50 and more common in those of British and Northern European ancestry; it appears less common in Latin America, but cases occur and many are found incidentally. Its frequency has fallen in recent decades.
Causes
- Genetic predisposition: mutations in SQSTM1 in many familial cases
- A possible environmental trigger, such as an earlier viral infection, has been proposed but not proven
- Cause unknown in most people
Risk factors
- Age over 50
- Family history of Paget disease
- Northern European ancestry
Pathophysiology
Large, overactive osteoclasts resorb bone; osteoblasts respond by laying down new bone quickly and chaotically, giving a mosaic pattern of woven bone. In the late stage, bone is thick and sclerotic but weak. Increased vascularity can raise cardiac output, and expanded bone can compress nerves.
Classification
- Monostotic: one bone affected
- Polyostotic: several bones affected
- Phases: lytic, mixed and sclerotic
Symptoms and signs
- Often asymptomatic; found by a raised alkaline phosphatase or on an X-ray
- Deep, aching bone pain, often worse at night
- Bowing of the femur or tibia and warmth over the affected bone
- Enlarging skull with headache and an increasing hat size
- Hearing loss from skull involvement
- Secondary osteoarthritis of the hip or knee
Diagnosis
- Clinical
- Bone pain or deformity in an older adult, or an incidental finding. Examination of long bones, skull and hearing.
- Tests
- Raised serum total or bone-specific alkaline phosphatase with normal calcium and phosphate; alkaline phosphatase is also used to monitor activity. Liver tests to exclude a hepatic source.
- Imaging
- Plain X-rays show thickened cortices, coarse trabeculae, bone enlargement and lytic areas (osteoporosis circumscripta in the skull). A radionuclide bone scan maps the extent of disease.
Differential diagnosis
- Osteoblastic bone metastases (e.g. prostate cancer)
- Primary hyperparathyroidism
- Osteomalacia
- Fibrous dysplasia
- Osteosarcoma
Goal of treatment
Relieve bone pain, suppress abnormal bone turnover and prevent or manage complications such as deformity, fracture and osteoarthritis.
Treatment
- Medical
- Bisphosphonates (zoledronic acid as a single infusion is highly effective) are first-line; vitamin D and calcium status is corrected first to avoid hypocalcaemia. Calcitonin is a second-line option.
- Medical
- Analgesics and non-steroidal anti-inflammatory drugs for pain and associated osteoarthritis.
- Surgical
- Fixation of fractures, osteotomy for severe bowing and joint replacement for advanced arthritis; bisphosphonates beforehand reduce bleeding from vascular bone.
- Follow-up
- Alkaline phosphatase periodically to detect relapse; hearing assessment when the skull is involved.
Complications
- Pathological fractures
- Secondary osteoarthritis
- Conductive or sensorineural hearing loss
- Spinal stenosis and nerve compression
- High-output heart failure
- Osteosarcoma (rare)
Prognosis
Usually good: treatment controls pain and bone turnover in most patients. The outlook is poor in the rare cases complicated by osteosarcoma.
Test yourself
Think of the answer, then tap the question to see it.
What is the typical laboratory finding in Paget disease of bone?
Isolated raised alkaline phosphatase with normal calcium and phosphate.
Which cell is primarily abnormal in Paget disease?
The osteoclast, which is enlarged and overactive, followed by disorganised osteoblastic bone formation.
What is the first-line drug class for symptomatic Paget disease?
Bisphosphonates, such as zoledronic acid.
Which rare malignant complication should be suspected with new pain and swelling in pagetic bone?
Osteosarcoma.
Related conditions
- Osteosarcoma
- Hearing loss (conductive and sensorineural, including sudden hearing loss)
- Hip Osteoarthritis
- Knee Osteoarthritis
- Heart failure
- Lumbar spinal stenosis
- Osteoporosis
- Primary hyperparathyroidism
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Paget disease of the bone (MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), 2025).
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