Investigations

Most cases of Paget’s disease are incidental findings in patients who are investigated for other conditions. In some instances patients may also present with obvious signs or symptoms related to the Paget’s disease of the bone (1).

The diagnosis of Paget’s disease is primarily radiological.

• the diagnosis of Paget’s disease should be confirmed by plain radiology of at least one skeletal site in all patients with the condition (2)
• a number of different radiological features have been described
  • in early disease - primarily lytic changes
    • V-shaped “cutting cone” in long bones
    • osteoporosis circumscripta in skull
  • in the combined phase - mixed lytic and sclerotic
    • cortical thickening
    • loss of corticomedullary distinction
    • accentuated trabecular markings
  • late phase - primarily sclerotic
    • thickening of long bones
    • increase in bone size
• plain radiographs are also useful for the diagnosis of secondary complications of the disease e.g. - arthritis or fracture

Other Investigations carried out in patients with Paget’s disease include:

• scintigraphy
  • use of 99mTc-labeled bisphosphonate tracer is more sensitive than x-rays
  • all patients with Paget’s disease should have scintigraphy performed to assess the extent of skeletal involvement
• biochemical tests reflect the increased bone turnover. Parameters of bone formation and resorption tend to change in unison.
  • alkaline phosphatase
    • reflects osteoblastic activity (also reflects disease activity)
    • the degree of elevation depends on the number of bones affected and partly on the duration of disease
    • plasma total alkaline phosphatase is usually increased
      • most frequently used and most useful biochemical marker for clinical management of the disease
    • bone specific alkaline phosphatase could be used in patients with
      • Paget’s disease, but without an elevation of plasma total alkaline phosphatase activity
      • liver disease
  • plasma calcium - usually normal but may be raised if the patient has been immobilised for a long period
  • increased urinary hydroxyproline - reflects osteoclastic activity; pyridinoline cross link is a new and more specific marker, but is expensive
• bone biopsy - rarely required, may be useful to differentiate osteoblastic metastases from osteosarcoma

Reference:

• (1) Langston AL, Ralston SH. Management of Paget's disease of bone. Rheumatology (Oxford). 2004;43(8):955-9.
• (2) Selby PL  et al. Guidelines on the management of Paget's disease of bone. Bone. 2002;31(3):366-73.