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    Urticaria

    Urticaria is a topic covered in the 5-Minute Emergency Consult.

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    Basics

    Description

    • Cutaneous mast and basophil cellular release of inflammatory mediators, primarily histamine:
      • Increased vascular permeability and pruritus
    • Edema of the epidermis as well as the upper and middle dermis:
      • More common in children and young adults
      • More common in women
      • More common in the atopic patient
    • 40% of patients with urticaria will have a component of angioedema:
      • Affects deeper subdermal and/or submucosal sites

    Pediatric Considerations
    • Urticaria is often the result of reactions to foods and infections
    • Swelling of distal extremities and acrocyanosis may be prominent in infants
    • Bullae may form in the center of the wheal, especially on legs and buttocks

    Etiology

    Acute:
    Presumptive trigger may be found, but majority of cases are idiopathic
    Course of <6 wk
    • Drugs:
      • Few have recurrent urticaria on later antigenic challenge
    • Foods or additives
    • Herbal medications, vaccines, opiates
    • Insect bites and stings
    • Connective tissue diseases
    • Endocrine disorders, especially Hashimoto's thyroiditis
    • Cancers, especially lymphoproliferative
    • Hormonal imbalance, pregnancy, menstrual cycle, exogenous estrogens
    • Infections:
      • Viral (including hepatitis, HIV)
      • Viral URI most common associated infection
      • Bacterial
      • Fungal
      • Parasitic
    • Inhaled or contact allergen
    • Emotional stress
    • Physical urticaria—>20 identified types, including:
      • Dermographism:
        • Most common physical form
        • Reaction to skin pressure
        • Linear wheals under tight clothing
        • Areas scratched with a firm object
      • Cholinergic:
        • Monomorphic wheals 2–3 mm
        • Bright red flare and intense pruritus
      • A response to elevated core temperature:
        • Hot bath
        • Fever
        • Exercise
      • Other rare forms:
        • Cold-induced (may be fatal in cold immersions)
        • Sun exposure
        • Aquagenic
    Chronic:
    Course of >6 wk
    • 75% idiopathic in nature
    • Autoimmune disease spectrum
    • Immune complex–induced
    • Often an unrecognized recurring physical urticaria
    • May be due to occult or subclinical infection or systemic disease

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    Citation

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    TY - ELEC T1 - Urticaria ID - 307335 ED - Barkin,Adam Z, ED - Barkin,Roger M, ED - Hayden,Stephen R, ED - Rosen,Peter, ED - Schaider,Jeffrey J, ED - Shayne,Philip, ED - Wolfe,Richard E, BT - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307335/all/Urticaria PB - Lippincott Williams & Wilkins ET - 5 DB - Emergency Central DP - Unbound Medicine ER -