What is the role of lab testing in the workup of complex regional pain syndrome (CRPS)?

Updated: Jun 20, 2018
  • Author: Gaurav Gupta, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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No specific diagnostic tests confirm the presence of CRPS. However, the differential diagnosis includes other neuropathic conditions, as well as a host of metabolic, systemic, vascular, and rheumatological disorders. Excluding other treatable but serious causes is indicated even in cases that present with the classic signs and symptoms.

  • Blood work for inflammatory arthropathy and vasculitis is indicated, which, in its basic form, includes complete blood count (CBC), erythrocyte sedimentation rate, C-reactive protein, antinuclear antibody, rheumatoid factor, complement fixation panel, serum immunoelectrophoresis, and a bone scan. Workup for diabetes should also include a test for hemoglobin A1c.

  • Electromyography (EMG) and nerve conduction studies are helpful in determining the neuroanatomy behind the symptoms and therefore in identifying the etiological process. For example, they confirm the presence of nerve injury, CRPS type II, nerve root avulsion, or a painful neuropathy due to diabetes, which may present with autonomic dysfunction.

  • Vascular studies of the affected limb(s) should also be considered.

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