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Paget disease of bone
Paget disease is a focal disorder of accelerated bone formation and resorption in older adults that produces large, thick and weak bone; it is usually discovered as a raised alkaline phosphatase with normal calcium and phosphate, and the preferred treatment when indicated is zoledronic acid as a single intravenous dose.
Why it matters in the exam
The exam presents an older adult without complaints with a high alkaline phosphatase and otherwise normal liver tests, or an older adult with bone pain, bowing of the tibia, skull enlargement ("the hat has become small") and hearing loss. Candidates are asked about the work-up (X-ray of the area and a bone scan to define extent) and the treatment.
Recurring points: indications for treatment are bone pain, involvement of the skull base, spine or weight-bearing bones near joints, preparation for surgery on affected bone and hypercalcaemia during prolonged immobilisation; zoledronic acid 5 mg as a single dose is the most effective, after vitamin D and calcium replacement to prevent hypocalcaemia; complications — fractures, deafness, nerve compression, high-output heart failure (rare) and osteosarcoma (less than 1%); and follow-up by alkaline phosphatase.
The disease is more common in people of northern European origin, has a familial component, and its frequency has fallen in recent decades. Most patients have no symptoms, and the diagnosis is made by chance on a blood test or an X-ray done for another reason. Pain in Paget disease may come from the bone itself or from osteoarthritis in a nearby joint, so the source of the pain is clarified before attributing it to the disease.
Follow-up tests are simple: alkaline phosphatase every few months after treatment, and then once a year.
Key points
- Accelerated formation and resorption — large, weak bone.
- High alkaline phosphatase, normal calcium and phosphate.
- Pelvis, spine, skull, femur, tibia; bone scan for extent.
- Treatment: zoledronic acid 5 mg as a single dose, after vitamin D.
- Complications: fractures, deafness, osteosarcoma (less than 1%).
Summary table
| Issue | Finding | Exam point |
|---|---|---|
| Laboratory | Raised alkaline phosphatase; normal calcium and phosphate | Normal GGT — bone source |
| Location | Pelvis, spine, skull, femur, tibia | Bone scan for extent |
| X-ray | Cortical thickening, lytic and sclerotic areas, bone enlargement | Lytic in the skull early on |
| Complications | Fractures, deafness, nerve compression, osteosarcoma (less than 1%) | New, worsening pain — suspect a tumour |
| Treatment | Zoledronic acid 5 mg intravenously, a single dose | Vitamin D and calcium beforehand |
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Sources
- Endocrine Society clinical practice guideline — Paget's disease of bone, 2014 — Diagnosis and treatment
- Paget's Association / international guideline for the diagnosis and management of Paget's disease of bone in adults, 2019 — Indications for bisphosphonate treatment
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Paget disease and other dysplasias of bone
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.