Diagnostic Evaluation for Paget's Disease of Bone
For suspected Paget's disease of bone, obtain plain radiographs of the suspected skeletal regions first, followed by total serum alkaline phosphatase with liver function tests, and then perform a radionuclide bone scan to determine the full extent of disease once diagnosis is confirmed. 1, 2
Initial Diagnostic Steps
Clinical Presentation to Recognize
- Most cases are asymptomatic and discovered incidentally on radiographs or as isolated elevation of serum alkaline phosphatase 3, 4
- Symptomatic patients present with: bone pain (most common), fractures, arthritis, nerve compression syndromes, hearing loss, or gait changes 4, 5
- Typical patient profile: Age over 50-55 years, with predilection for pelvis, spine, skull, femur, tibia, and humerus 1, 3, 4
First-Line Imaging
- Plain radiographs of suspected skeletal regions are the first-line investigation, showing characteristic mixed osteolytic and osteosclerotic appearance 1, 2
- These radiographs establish the diagnosis based on typical features 3, 4
Biochemical Testing
- Total serum alkaline phosphatase (ALP) is the primary biochemical screening test and must be combined with liver function tests to exclude hepatic causes of elevation 1, 6, 2
- Complete metabolic panel should include: alkaline phosphatase, calcium, 25-hydroxy-vitamin D, phosphate, and parathyroid hormone levels to exclude other metabolic bone diseases 6
- More specific bone turnover markers (PINP or CTX) can be used if needed for clarification 1
Extent of Disease Assessment
- Radionuclide bone scan is recommended once diagnosis is confirmed to determine the full extent of metabolically active disease throughout the skeleton 1, 5, 2
- This is critical because Paget's disease can be monostotic or polyostotic, and identifying all affected sites influences management 2, 7
Key Differential Diagnosis Features
Paget's disease is distinguished from other pathologies by: 1
- Family history of Paget's disease
- Typical localization to pelvis or skull
- Elevated alkaline phosphatase with normal liver function
- Bone deformities on imaging
- Age of onset over 50 years
Important Caveats
- Do not rely on ALP alone without liver function tests, as hepatic disease can cause similar elevations 1, 2
- Ensure adequate vitamin D and calcium levels are checked before initiating any treatment, as bisphosphonate therapy can precipitate hypocalcemia 1
- Asymptomatic patients with incidental findings still require full diagnostic workup to assess disease extent and risk of complications 3, 4