investigations

Last edited 12/2020 and last reviewed 12/2020

Investigations

  • WBC - usually raised
  • ESR and CRP - usually raised
  • hypergammaglobulinaemia
  • rheumatoid factor - absent

Imaging for suspected psoriatic arthritis and other peripheral spondyloarthritides (1)

  • offer plain film X-ray of symptomatic hands and feet for people with suspected peripheral spondyloarthritis in these areas
  • If a diagnosis cannot be made from the plain film X-ray, consider ultrasound of:
    • the hands and feet to assess for joint involvement
    • suspected enthesitis sites
  • consider plain film X-rays, ultrasound and/or MRI of other peripheral and axial symptomatic sites
  • interpret a positive HLA-B27 result as increasing the likelihood of peripheral spondyloarthritis.
  • if a diagnosis of peripheral spondyloarthritis is confirmed, offer plain film X-ray of the sacroiliac joints to assess for axial involvement, even if the person does not have any symptoms.
  • radiology - characteristic features include (2):
    • joint erosions and joint space narrowing
    • bony proliferation including periarticular and shaft periostitis,
    • osteolysis including "pencil in cup' deformity,
    • acro-osteolysis
    • ankylosis,
    • spur formation,
    • spondylitis

Erosive changes of the DIP seen in radiography may be used as both a sensitive and specific diagnostic feature of psoriatic arthritis (2).

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