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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Paget disease of bone

Rheumatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Neurological loss or pathological fracture

New limb weakness, sphincter dysfunction, cranial-nerve compromise, sudden deformity or inability to bear weight can reflect Pagetic spinal compression, skull-base complication or fracture through weak bone.

Action: Immobilise and image suspected fracture, perform urgent neurological assessment, and involve spinal, neurosurgical or orthopaedic teams immediately; biochemical treatment must not delay decompression or stabilisation.

Overview

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 a local remodelling disorder, not generalised osteoporosis. Ask about deep focal bone pain, warmth, limb bowing, increasing hat size, headache, hearing change, dental fit, joint-related pain, radicular symptoms, gait disturbance, fractures and family history. Examine skull contour, hearing, spinal neurology, limb alignment, local warmth, adjacent joint range and gait. Most affected adults are older than 50, and calcium and phosphate are normally preserved unless another disorder or prolonged immobilisation intervenes.

The diagnostic sequence separates confirmation, mapping and activity. A targeted radiograph establishes characteristic structure: coarsened trabeculae, cortical thickening, expansion, mixed lysis and sclerosis, or a blade-of-grass lytic front. Total ALP with liver tests is the usual biochemical screen. Once confirmed, radionuclide scintigraphy identifies other active sites. A normal ALP cannot exclude a small monostotic lesion, so bone-specific markers help when liver disease or limited burden obscures signal.

Aetiology

01

Genetic susceptibility

Familial clustering and variants affecting osteoclast regulation, especially SQSTM1, contribute substantially; family history often predicts earlier onset and more extensive involvement.

02

Age and geography

Disease is uncommon before 50 and becomes more prevalent with age; frequency varies geographically and has declined in severity in several historically high-prevalence regions.

03

Uncertain environmental triggers

Environmental influences have been proposed, but no single infection or exposure is established as the direct cause and routine antimicrobial investigation has no role.

Pathophysiology

  1. 1
    Excess osteoclast activity

    Focally increased osteoclast number and activity creates rapid disorganised resorption; early lesions may be predominantly lytic and advance through affected bone.

  2. 2
    Chaotic compensatory formation

    Osteoblasts replace resorbed bone quickly but lay woven and lamellar tissue in a mosaic pattern rather than normal aligned architecture.

  3. 3
    Enlarged weak bone

    Resulting bone can be expanded, hypervascular and mechanically abnormal; it may bow, fissure or fracture despite appearing sclerotic and dense.

  4. 4
    Local structural effects

    Expansion and deformity alter adjacent joint loading and can narrow neural foramina, compress spinal or cranial nerves and complicate surgery through abnormal anatomy.

Clinical features and red flags

Incidental biochemical signal

An isolated raised ALP with normal liver markers in an older adult commonly triggers investigation, although the value reflects total active skeletal burden.

Focal bone pain

Pagetic pain is often deep, localised and present at rest, sometimes with warmth; mechanical adjacent-joint pain follows movement and loading.

Long-bone deformity

Anterior tibial or lateral femoral bowing changes gait and concentrates tensile stress, increasing fissure and complete fracture risk.

Skull involvement

Increasing hat size, frontal bossing, headache and progressive hearing impairment suggest skull disease, while cranial neuropathy signals complicated expansion.

Spinal involvement

Back pain, stenotic claudication, radiculopathy or myelopathy can result from enlarged vertebrae, degeneration, fracture or epidural compromise.

Malignant warning change

New relentless pain, rapid enlargement, focal swelling or a mass within known Pagetic bone is atypical and requires urgent malignancy assessment.

Red flags requiring action

  • 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.

Investigations

  1. 01
    First-line total ALP and liver testsFirst stepFirst line
    Why
    Screen for increased bone turnover and distinguish a likely skeletal source from hepatobiliary ALP elevation.
    Interpretation and limitations
    Raised ALP with otherwise normal liver tests supports active skeletal turnover but is nonspecific; normal ALP may occur in monostotic or quiet disease.
  2. 02
    Confirmatory targeted radiographsConfirmatory
    Why
    Demonstrate expansion, cortical thickening, trabecular coarsening, lysis and sclerosis at a suspected site.
    Interpretation and limitations
    Characteristic films usually establish diagnosis; aggressive permeative destruction, cortical breakthrough or soft-tissue mass requires tumour referral.
  3. 03
    Extent-defining bone scan
    Why
    Map additional metabolically active sites after radiographic confirmation and guide dedicated anatomical imaging.
    Interpretation and limitations
    Focal uptake is sensitive but also occurs with metastasis, fracture and arthritis; correlate each unexpected focus with radiography or cross-sectional imaging.
  4. 04
    Alternative turnover markers
    Why
    Assess activity when total ALP is normal despite limited disease or cannot be interpreted due to liver pathology.
    Interpretation and limitations

Differential diagnosis

01

Metastasis or sarcoma

Focal sclerosis, lysis and pain can be malignant; aggressive destruction, soft-tissue mass, disproportionate pain or atypical scan pattern needs oncological imaging and biopsy planning.

02

Osteoarthritis

Hip, knee or spinal osteoarthritis commonly coexists and may generate the pain; joint-line pattern and targeted imaging prevent treatment of an incidental Pagetic site.

03

Hyperparathyroid bone disease

Hyperparathyroidism can raise ALP and remodel bone diffusely, but calcium, PTH and distribution differ; Paget disease is usually focal with normal calcium.

04

Fibrous dysplasia

Fibrous dysplasia also expands abnormal bone, often presenting earlier with ground-glass matrix; age, distribution and radiographic boundaries guide distinction.

Management

01First-line diagnosisConfirm locally, map globallyFirst stepFirst lineFocal abnormal imaging, compatible pain or unexplained bone-source ALP elevation raises suspected Paget disease.+
  1. 1Take a site-specific history and examination, check total ALP with liver profile, calcium, phosphate, kidney function and vitamin D, and obtain targeted radiographs.
  2. 2Once films are characteristic, arrange radionuclide scintigraphy to define distribution and image unexpected high-uptake sites anatomically when uncertain.
  3. 3Use bone-specific ALP or another marker if monostotic disease is likely or hepatic ALP obscures activity, reserving biopsy for diagnostic or malignant uncertainty.
  4. 4For each site, decide whether symptoms arise from active bone, adjacent osteoarthritis, fracture, deformity or neural compression.
02Preferred symptom treatmentSuppress painful active remodelling

Complications

01

Deformity and fracture

Bowing of femur or tibia, skull enlargement and fissure or complete pathological fractures arise because enlarged mosaic bone is mechanically inefficient.

02

Secondary osteoarthritis

Altered alignment and subchondral change increase load across hips, knees and spine, causing degenerative pain that may persist after biochemical suppression.

03

Neurological and hearing loss

Skull or vertebral expansion can produce hearing impairment, cranial neuropathy, spinal stenosis, cord compression or rarely skull-base and hydrocephalus complications.

04

Rare sarcomatous change

Osteosarcoma or another sarcoma is uncommon but aggressive; escalating pain, swelling, a mass or new lytic destruction must not be dismissed as turnover.

Monitoring and follow-up

  • Document pretreatment pain location and character so improvement in deep bone pain is not confused with unchanged osteoarthritis or radicular symptoms.
  • Repeat the chosen turnover marker, often total ALP, around three to six months after bisphosphonate treatment and use its nadir as a comparator.
  • Review sooner for new weakness, gait change, hearing symptoms, deformity, focal swelling or rapidly changing pain regardless of the latest ALP.
  • After zoledronate, distinguish the expected short acute-phase reaction from persistent fever, focal infection, symptomatic hypocalcaemia or kidney injury.
  • Long-term follow-up can be symptom-led with periodic biochemical review; biochemical relapse without symptoms does not automatically mandate retreatment.
  • Maintain falls, joint, hearing and mobility support because fixed structural consequences may persist after turnover suppression.

Special situations

ALP measures burden

Total ALP rises more in extensive active disease and may remain normal in one small lesion; it is neither a pain scale nor cancer test.

Scan and film differ

Scintigraphy sensitively maps activity, whereas radiography establishes Pagetic structure; a hot focus alone is not specific enough for diagnosis.

Pain needs attribution

An affected pelvis beside an arthritic hip creates two possible generators; examination and correlated imaging prevent futile biochemical treatment.

Dense is not strong

Pagetic bone can look sclerotic while its mosaic architecture and deformity make it susceptible to fissure and complete fracture.

New pain may be malignant

Rare sarcoma is dangerous enough that a rapid qualitative change in pain, swelling or imaging deserves urgent specialist evaluation.

Common pitfalls

  1. 01

    Do not diagnose Paget disease from raised ALP alone; confirm a skeletal source, image characteristically and consider liver disease, fracture and malignancy.

  2. 02

    Do not use radionuclide uptake as a stand-alone diagnosis because metastasis, arthritis and healing fracture can all be active.

  3. 03

    Do not assume every painful joint next to Pagetic bone responds to bisphosphonate; secondary osteoarthritis often needs joint-directed care.

  4. 04

    Do not chase biochemical normalisation in an asymptomatic person without a defined clinical objective.

  5. 05

    Do not let normal ALP reassure against cord compression, fracture or sarcoma when new structural or neurological features are present.

  6. 06

    Do not give zoledronate before correcting hypocalcaemia or important vitamin-D deficiency and confirming renal suitability.

Practice

Two practice questions

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Question 1 of 2
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RheumatologyOriginal SBA

Mapping confirmed disease

A 72-year-old has a raised bone-source ALP and a pelvic radiograph showing typical cortical thickening, expansion and trabecular coarsening. Which next investigation best establishes the full skeletal extent?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • UK Paget disease clinical guidelineDiagnosis, imaging, symptom-directed treatment and complications.
  • Paget Association clinical managementUK implementation of imaging, markers, zoledronate and follow-up.
  • Paget Association treatment guidanceTreatment indications, administration and expected response.
  • Aclasta Summary of Product CharacteristicsPaget regimen, renal threshold and mineral safety.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Treatment is driven mainly by Paget-attributable bone pain and selected complications, not by normalising every marker. Zoledronic acid produces prolonged suppression, but osteoarthritis, fixed deformity or nerve compression may persist despite falling ALP. Joint replacement, fixation, decompression, hearing support and ordinary analgesia remain important. Evidence does not support routine bisphosphonate solely to reduce bleeding before Pagetic bone surgery.

Key points

  • 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.
  • 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.
    • Bone-specific ALP, PINP or urinary NTX can reflect remodelling; use the same marker for follow-up without substituting it for clinical outcome.
  • 05
    CT or MRI for complications
    Why
    Define neural compression, occult fracture, skull-base anatomy, malignant change or complex surgical relationships.
    Interpretation and limitations
    MRI demonstrates marrow and neural structures; CT shows cortex and mineralised anatomy; urgency follows neurological deficit or aggressive change, not ALP concentration.
  • 06
    Pre-bisphosphonate safety tests
    Why
    Prevent hypocalcaemia and kidney injury and identify another metabolic explanation.
    Interpretation and limitations
    Check adjusted calcium, phosphate, vitamin D and creatinine clearance; correct deficiencies and avoid intravenous zoledronate below its licensed renal threshold.
    • Preferred
    Deep focal pain is attributable to active Paget disease and no urgent structural complication dominates.
    +
    1. 1Correct vitamin-D deficiency and hypocalcaemia, verify creatinine clearance, review dental and pregnancy context, and explain the transient acute-phase reaction.
    2. 2Offer one 5 mg intravenous zoledronic-acid infusion when suitable because UK guidance identifies it as most likely to give a favourable pain response.
    3. 3Use oral risedronate 30 mg daily for two months when intravenous treatment is unsuitable but swallowing, absorption and renal function permit.
    4. 4Review pain and baseline marker after treatment; never repeat solely because ALP has not reached the middle of the reference range.
    03Complication escalationTreat anatomy rather than markerEscalationFracture, deformity, joint failure, hearing impairment or neurological compression causes disability or threatens function.+
    1. 1Use urgent fracture stabilisation and spinal or neurosurgical assessment for instability or neurological loss; remodelling suppression is not decompression.
    2. 2Refer disabling secondary hip or knee osteoarthritis for arthroplasty and alert surgeons to deformity, anatomy, vascularity and bone-quality considerations.
    3. 3Arrange audiology and hearing support because bisphosphonate has not reliably prevented hearing-loss progression.
    4. 4Do not give bisphosphonate routinely solely to reduce operative blood loss; let the surgical team plan anatomy, vascularity and haemostasis.
    04Urgent malignancy routeInvestigate aggressive changeEscalationKnown or suspected Paget disease develops rapidly escalating pain, swelling, a mass or destructive imaging.+
    1. 1DefinitiveObtain urgent radiography and MRI or CT of the whole lesion, avoiding unplanned biopsy that could compromise definitive tumour surgery.
    2. 2Refer through a bone-sarcoma service so staging and image-guided biopsy occur along an oncologically safe tract.
    3. 3Continue analgesia and protect weight-bearing bone while malignancy, fracture and infection are differentiated; ALP alone cannot resolve them.
    Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
    Preferred bisphosphonate for Paget-attributable bone pain because it provides strong durable turnover and pain responses.

    Zoledronic acid

    Give 5 mg by intravenous infusion over at least 15 minutes as a single treatment, with adequate hydration, calcium and vitamin D; retreatment follows clinical relapse rather than a fixed calendar.

    Avoid creatinine clearance below 35 mL/min, hypocalcaemia and pregnancy. Correct vitamin-D deficiency, check creatinine and warn about transient fever, myalgia and headache; jaw and femur complications are rare.

    Licensed oral alternative when bisphosphonate treatment is indicated but intravenous zoledronate is unsuitable or not preferred.

    Risedronate sodium

    Take 30 mg orally once daily for two months, at least 30 minutes before food, drink except water, or another medicine; remain upright for at least 30 minutes.

    Avoid hypocalcaemia, severe renal impairment, oesophageal emptying disorders and inability to remain upright; separate calcium, iron and antacids and avoid during pregnancy.

    Treats coexisting mechanical or fracture-related pain while its anatomical source is defined; it does not suppress Pagetic remodelling.

    Paracetamol

    Use 500 mg–1 g orally at intervals of at least four hours when needed, maximum 4 g in 24 hours for a suitable adult, with a lower ceiling for low weight, frailty or liver risk.

    Avoid duplicate combination products and reduce exposure with hepatic disease or excess alcohol; persistent pain requires diagnostic reassessment rather than automatic escalation.