Table 2 Recommended investigations in urticaria according to type and subtype
From: Insights and advances in chronic urticaria: a Canadian perspective
Type | Subtype | Initial tests | More extensive tests |
|---|---|---|---|
Spontaneous urticaria | Acute spontaneous urticaria | None | None* |
Chronic spontaneous urticaria | CBC with differential and ESR or CRP | (i) Allergen skin testing, and measurement of allergen-specific IgE levels are seldom required in CSU. Measurement of IgG levels to foods has no diagnostic value. (ii) functional autoantibodies; (iii) thyroid hormones and autoantibodies; (iv) physical tests; (v) tryptase; (vi) autologous serum skin test; (vii) lesional skin biopsy | |
Inducible urticaria | Cold urticaria | Cold provocation and threshold test: apply an ice cube to the skin for 5 min, or, if available, use a TempTest; urticaria appears on re-warming | CBC with differential and ESR/CRP cryoproteins |
Delayed pressure urticaria | Pressure test | None | |
Heat urticaria | Heat provocation and threshold test | None | |
Solar urticaria | UV and visible light of different wave lengths | Rule out other light-induced dermatoses | |
Symptomatic dermographism | Elicit dermographism by stroking skin firmly with a tongue depressor or, if available, use a FricTest | None | |
Aquagenic urticaria | Wet cloths at body temperature applied for 20 min | None | |
Cholinergic urticaria | Exercise and hot bath provocation | None | |
Contact urticaria | None |