Laboratory evaluation can be used as a measure to determine disease severity, responsiveness to treatment and prognosis, in addition to their role as a diagnostic tool. Tests such as autologous serum skin test (ASST) and basophil activation test (BAT) are useful for detection of autoantibodies against IgE. Moreover elevated levels of c-reactive protein (CRP), erythrocyte sedimentation rate (ESR), certain interleukins and tumor necrosis factor-alpha have been reported in urticaria patients. Laboratory evaluations that can determine disease activity are autologous serum skin test (ASST), c-reactive protein (CRP) and IL-6.

• Autologous serum skin test (ASST) and basophil activation test (BAT) are two tests that are capable of detecting any autoantibodies against IgE for FcεRI.^[1][2]
  • Although ASST is not a specific test, positive results can determine active disease, mast cells and basophils activation and possible reduction in basophils.
  • Interestingly positive autologous serum skin test (ASST) could be related to better prognosis.
  • Moreover positive autologous serum skin test (ASST) seems to be related to slower response to omalizumab.
• C-reactive protein (CRP) is also related to disease activity and treatment response in urticaria.^[3][4][5]
  • It’s elevated level is also associated with positive autologous serum skin test (ASST) and elevated levels of erythrocyte sedimentation rate (ESR), leukocytes, neutrophils and IL-6.
  • Elevated CRP is related to better response to oral cyclosporine therapy and conversely poor response to antihistamines.
  • In contrast to other inflammatory conditions, urticaria patients usually present with lower quantitative level of CRP.
• Complete blood count (CBC) with differential^[6]
• Erythrocyte sedimentation rate (ESR): Elevated levels might be related to autoimmune disease.^[6]
• Interleukins:
  • Elevated level of IL-6 is related to disease activity in urticaria.^[4]
  • IL-18, one of the IL-1 family cytokines, has been present in serum specimens of nearly all patients with chronic spontaneous urticaria. Nevertheless more studies required to determine it’s exact role in the pathogenesis of this subtype.^[7][8]
  • The following table is a summary of possible elevated interleukins in urticaria:^[8][1][9]

• Elevated levels of tumor necrosis factor-alpha has been detected in some patients with chronic spontaneous urticaria.
• The following table is a summary of useful markers to determine disease severity and response to treatment in urticaria:^{[1][10][11][12][13][14]}

• High levels of vascular endothelial growth factor (VEGF) has been detected in urticaria patients, which is probably related to it’s effect on vascular permeability.
• It is recommended to search for paraproteins, hepatitis B, hepatitis C, systemic lupus erythematosus and inflammatory bowel disease in patients with confirmed diagnosis of urticaria vasculitis.^[15]