Synopsis
Identify focal disordered bone remodelling, confirm suspected sites radiographically, map active involvement, distinguish Paget-related pain from adjacent osteoarthritis, and use symptom-directed bisphosphonate treatment while recognising neurological, fracture and malignant complications.
- Paget disease is focal accelerated bone turnover producing enlarged, disorganised and mechanically weak bone; pelvis, spine, femur, tibia and skull are common sites.
- Many cases are incidental after isolated raised ALP or characteristic radiography; confirm suspected sites with plain films and check total ALP with liver tests.
- After radiographic diagnosis, radionuclide bone scintigraphy maps the full extent of metabolically active disease; uptake is sensitive but not specific.
- Normal total ALP does not exclude monostotic disease; bone-specific ALP, PINP or urinary NTX can support activity assessment when liver disease confounds interpretation.
- Treat bone pain attributable to active Paget disease with a bisphosphonate; one zoledronic-acid 5 mg infusion provides the most durable response and favourable pain effect.
- Do not treat an ALP value alone or pursue complete biochemical normalisation in every asymptomatic patient; decide whether a lesion explains symptoms or threatens a defined complication.
- Pain may instead arise from secondary osteoarthritis, fissure fracture, nerve compression, spinal stenosis or malignancy, each needing its own management.
- Check calcium, vitamin-D status and kidney function before potent bisphosphonate treatment and warn that fever and myalgia commonly follow first zoledronate infusion.
Key red flags
Rapidly increasing focal bone pain, enlarging swelling, a soft-tissue mass or new destructive imaging requires urgent assessment for sarcomatous transformation or another malignancy.
New weakness, gait disturbance, sensory loss, bladder or bowel dysfunction, dysphagia or brainstem symptoms may indicate neural compression and needs expedited cross-sectional imaging.
Sudden severe limb or hip pain with deformity or inability to bear weight suggests pathological fracture through Pagetic bone.
Marked hypercalcaemia, dehydration, confusion or kidney injury during immobilisation is unusual but can occur with extensive active disease and requires acute treatment.
Investigation priorities
Screen for increased bone turnover and distinguish a likely skeletal source from hepatobiliary ALP elevation.
Management branches
Focal abnormal imaging, compatible pain or unexplained bone-source ALP elevation raises suspected Paget disease.
- Take a site-specific history and examination, check total ALP with liver profile, calcium, phosphate, kidney function and vitamin D, and obtain targeted radiographs.
- Once films are characteristic, arrange radionuclide scintigraphy to define distribution and image unexpected high-uptake sites anatomically when uncertain.
- Use bone-specific ALP or another marker if monostotic disease is likely or hepatic ALP obscures activity, reserving biopsy for diagnostic or malignant uncertainty.
- For each site, decide whether symptoms arise from active bone, adjacent osteoarthritis, fracture, deformity or neural compression.
Deep focal pain is attributable to active Paget disease and no urgent structural complication dominates.
- Correct vitamin-D deficiency and hypocalcaemia, verify creatinine clearance, review dental and pregnancy context, and explain the transient acute-phase reaction.
- Offer one 5 mg intravenous zoledronic-acid infusion when suitable because UK guidance identifies it as most likely to give a favourable pain response.
- Use oral risedronate 30 mg daily for two months when intravenous treatment is unsuitable but swallowing, absorption and renal function permit.