Paget's disease of the bone
Introduction
Paget's disease is a disease of increased but uncontrolled bone turnover. It is thought to be primarily a disorder of osteoclasts, with excessive osteoclastic resorption followed by increased osteoblastic activity. Paget's disease is common (UK prevalence 5%) but symptomatic in only 1 in 20 patients. The skull, spine/pelvis, and long bones of the lower extremities are most commonly affected.
Epidemiology
- Incidence: 10.00 cases per 100,000 person-years
- Peak incidence: 70+ years
- Sex ratio: more common in males 1.5:1
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Predisposing factors
- increasing age
- male sex
- northern latitude
- family history
Clinical features
Clinical features - only 5% of patients are symptomatic
- the stereotypical presentation is an older male with bone pain and an isolated raised ALP
- bone pain (e.g. pelvis, lumbar spine, femur)
- classical, untreated features: bowing of tibia, bossing of skull
Investigations
Investigations
- raised alkaline phosphatase (ALP) - calcium and phosphate are typically normal
- other markers of bone turnover include: procollagen type I N-terminal propeptide (PINP), serum C-telopeptide (CTx), urinary N-telopeptide (NTx), and urinary hydroxyproline
- skull x-ray: thickened vault, osteoporosis circumscripta
Management
Indications for treatment include bone pain, skull or long bone deformity, fracture, periarticular Paget's
- bisphosphonate (either oral risedronate or IV zoledronate)
- calcitonin is less commonly used now
Complications
Complications
- deafness (cranial nerve entrapment)
- bone sarcoma (1% if affected for > 10 years)
- fractures
- skull thickening
- high-output cardiac failure