Table 3. Relevant investigations for urticaria.
| Classification of urticaria/investigation | CBC | ESR or CRP | TA/TFT ANA | IgE | ASST | C4 | Skin biopsy | Physical challenge |
|---|---|---|---|---|---|---|---|---|
| Acute urticaria | - | - | - | + | - | - | - | - |
| Chronic spontaneous urticaria | + | + | + | - | - | + | - | - |
| Inducible urticaria | - | - | - | - | - | - | - | + |
| Contact urticaria | - | - | - | + | - | - | - | - |
| Angio-edema without wheals | - | - | - | - | - | + | - | - |
| Urticarial vasculitis | + | + | - | - | - | + | + | - |
| Autoinflammatory syndrome | + | + | - | - | - | - | - | - |
Modified from Grattan, et al. Br J Dermatol 2007;157:1116-2325), with permission of Wiley & Sons Inc.
CBC, complete blood count; ESR, erythrocyte sedimentation rate: CRP, C-reactive protein; TA, thyroid antibody; TFT, thyroid function test; ANA, antinuclear antibody; ASST, autologous serum skin test.