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Chronic Urticaria Laboratory Tests Case One Case One Chronic

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					                                            Allergy-Immunology & Laboratory Services                                             Allergy-Immunology & Laboratory Services



                Chronic Urticaria                                                      Case One
                Laboratory Tests                                                       ν   A 6yo boy presents with a 6-month history of
                                                                                           recurrent urticaria occurring a few times a week
                      Dr Sharon Choo
                        Department of                                                  ν   Each hive lasts few hours and leaves no bruising
                 Allergy & Immunology, RCH                                             ν   No history of bites, vaccinations or medications
                                                                                       ν   No family history of hives or organ-specific
                   Saturday    22nd
                                  May 2010
                Practical Paediatrics Program
                                                                                           autoimmune disease; some relatives with allergy
                         Part 2, 2010                                                  ν   No fevers, weight loss or joint symptoms
      An alliance between Divisions of General Practice
               and the Royal Children’s Hospital
                 www.rch.org.au/kidsconnect
                 (RCH Primary Care Liaison)




                                            Allergy-Immunology & Laboratory Services                                             Allergy-Immunology & Laboratory Services




Case One                                                                               Chronic Urticaria
ν   Differential Diagnosis?                                                            ν   Itchy hives lasting >6 weeks
                                                                                       ν   Each hive lasts <24 hours
ν   Investigations?                                                                    ν   Up to 50% have angiodema
                                                                                       ν   Cause identified in <20%: immunodysregulation?
ν   Management?                                                                        ν   70% resolve within 3 years, 90% after 5 years




                                            Allergy-Immunology & Laboratory Services                                             Allergy-Immunology & Laboratory Services




Chronic Urticaria: Causes?                                                             Chronic Urticaria: Diagnosis
ν   Environmental allergens                                                            ν   History, history and history
ν   Physical factors e.g. cold urticaria                                               ν   Differential diagnoses to consider:
ν   Intercurrent illnesses and stress                                                         Eczema
                                                                                              Erythema multiforme
ν   Autoimmune Chronic Urticaria: more severe
                                                                                              Contact urticaria
       1/3 of chronic urticaria have autoantibodies against:
          FcEpsilon Receptor                                                                  Urticarial vasculitis
          IgE                                                                                 Autoinflammatory urticaria syndromes (e.g.
       Associated with other autoimmune diseases                                              NOMID/CINCA, Muckle-Wells, FCAS)
          Coeliac disease                                                                     Dermatographism
          Autoimmune thyroid disorders
                                          Allergy-Immunology & Laboratory Services                                            Allergy-Immunology & Laboratory Services




Chronic Urticaria: Investigations                                                    Chronic Urticaria: Management
ν   Investigations are not usually required                                          ν   Avoid triggers:
ν   If investigations are required:                                                         Physical factors and stress
       [Autologous serum skin test]                                                         Aspirin and NSAIDs
       TSH and thyroid antibodies                                                    ν   H1 receptor antagonist
       Other autoantibodies e.g. ANA, Coeliac antibodies                                    Cetirizine or Fexofenadine
       Total IgE                                                                            Desloratidine or Levocetirizine
       Serology e.g. Streptococcal, H. pylori, Mycoplasma                            ν   H2 receptor antagonist
                                                                                     ν   Leukotriene antagonist
                                                                                     ν   Immunosuppression e.g. cyclosporin




                                          Allergy-Immunology & Laboratory Services                                            Allergy-Immunology & Laboratory Services




Case Two                                                                             Case Two
ν   16yo female patient with a two year history of                                   ν   Differential Diagnosis?
    urticaria and angio-oedema.
ν   Hives: daily, different parts of the body, itchy,                                ν   Investigations?
    variable in size and lasted less than 24 hours.
ν   Angioedema: daily face swelling +/- sensation of                                 ν   Management?
    throat swelling
ν   Exacerbating factors: stress, swimming,
    NSAIDS, chocolate and artificial juices.
ν   Family Hx included allergy and thyroid disorders.




                                          Allergy-Immunology & Laboratory Services                                            Allergy-Immunology & Laboratory Services




Coeliac Disease Tests: FAQs                                                          Other Autoantibody Tests: FAQs
ν   What happened to Gliadin antibodies?                                             ν   How to interpret ANA in a child?
ν   What happened to Endomysial antibodies?                                          ν   How to interpret a low titre ANA?
ν   What is DGP?
ν   DGP IgA vs DGP IgG?                                                              ν   How to interpret thyroid antibody results?
ν   Interpretation of a child’s results vs an adult
ν   When to measure total IgA?
ν   How low is “low” IgA?
ν   What does a “DQ2 positive” result mean?
                                                                          Allergy-Immunology & Laboratory Services                                                                              Allergy-Immunology & Laboratory Services




      Skin Testing vs Specific IgE                                                                                           Two Specific IgE methods
      SPT   Advantages                                         Serum sIgE Advantages
                                                                                                                             ν    UniCAP/ImmunoCAP (Phadia)
      1.     Minor scratch, itch if +ve                        1. Widely available                                           ν    Immulite (Siemens)
      2.     Results in 30 mins                                2. No risk of systemic                                        ν    Results may be different
      3.     Results are visible and                               allergic reaction in
             compelling                                            patients
      4.     Better sensitivity                                3. Can be done where skin                                     ν    Use a lab that provides quantitative results
      5.     Most allergens                                        disease
      6.     Can use fresh foods                               4. No effect by
             (specialist practice)                                 antihistamine




                                                                          Allergy-Immunology & Laboratory Services                                                                              Allergy-Immunology & Laboratory Services




                                                                                                                             How do we interpret specific IgE?
                                                                                                                                                                                       Probability of an IgE
                                                                                                                           Value of sIgE                                                mediated allergic
                                                                                                                                                                                            reaction




                                                                                                                           Value of sIgE                                               Severity of an allergic
                                                                                                                                                                                              reaction



                                                                J Allergy Clin Immunol 2008;121:1219-24                      1. Sicherer and Sampson. J Allergy Clin Immunol 2010; 125: S116-25.




What is the NPV of a low                                                                                             What is the PPV of a high
or negative specific IgE?                                                                                            positive specific IgE?
                                                                          Allergy-Immunology & Laboratory Services                                                                              Allergy-Immunology & Laboratory Services




Study          Notes                                 Egg          Milk        PN          Soy          Wheat         Study           Notes                                Egg          Milk        PN          Soy         Wheat
                                                     NPV          NPV         NPV         NPV          NPV                                                                PPV          PPV         PPV         PPV         PPV


                                                                                                                     Sampson &       N=100. High prevalence of
Sampson &      N=100. High prevalence of                                                                             Ho 1997         positive food allergy (egg 73%,
Ho 1997        positive food allergy (egg 73%,       88%          100%        85%         95%          97%           (JACI)1         milk 50%, PN 49%, soy 28%,           >95%         >95%        >95%        >50%        >75%
(JACI)1        milk 50%, PN 49%, soy 28%,            (<0.35)      (<0.35)     (<0.35)     (<0.35)      (<0.35)                       wheat 22%) Adjusted                  (>6)         (>32)       (>15)       (>65)       (>100)
USA            wheat 22%)                                                                                                            prevalence of 10%.


                                                     >90%         >95%        85%         >95%         >95%          Roberts         N=157. High prevalence of PN
               Adjusted for prevalence 10%
                                                     (< 0.6)      (0.8)       (<0.35)     (<2)         (<5)          Lack 2005       allergy (52%)                                                 >95%
                                                                                                                     (JACI)3                                                    -          -                         -          -
                                                                                                                                                                                                   (≥ 15)
Roberts
Lack 2005      157 subjects with high                                         68%
(JACI)3        prevalence of PN allergy (52%)                                 (<0.35)
UK


1. Sampson HA, Ho DG. Journal of Allergy & Clinical Immunology. 1997 Oct;100(4):444-51                               1. Sampson HA, Ho DG. Journal of Allergy & Clinical Immunology. 1997 Oct;100(4):444-51
2. Roberts G, Lack G. Journal of Allergy & Clinical Immunology. 2005 Jun;115(6):1291-6                               2. Roberts G, Lack G. Journal of Allergy & Clinical Immunology. 2005 Jun;115(6):1291-6
         How do we use sIgE?                                          Allergy-Immunology & Laboratory Services
                                                                                                                          How do we use sIgE?                                          Allergy-Immunology & Laboratory Services



        1.       Confirm IgE food allergy                                                                                However if ….
                 Convincing                 Any positive                             POSITIVE
                   history                      sIgE                                                                         Convincing                                                          CANNOT EXCLUDE
                                                                                    DIAGNOSIS                                                                Negative sIgE
                                                                                                                               history                                                          IgE FOOD ALLERGY


        2.       Exclude IgE food allergy
                                                                                                                                                                                                            ?
                                                                                                                               Unlikely                     Positive sIgE
                                                                                                                               history
                 Unlikely                  Negative sIgE                         UNLIKELY IgE
                 history                                                        FOOD ALLERGY
                                                                                                                             High sensitivity yields false positives

1. Sicherer and Sampson. J Allergy Clin Immunol 2010; 125: S116-25.                                              1. Sicherer and Sampson. J Allergy Clin Immunol 2010; 125: S116-25.
2. Sampson HA, Ho DG. Journal of Allergy & Clinical Immunology. 1997 Oct;100(4):444-51                           2. Sampson HA, Ho DG. Journal of Allergy & Clinical Immunology. 1997 Oct;100(4):444-51




                                                                      Allergy-Immunology & Laboratory Services                                                                         Allergy-Immunology & Laboratory Services




             Specific IgE Tests: FAQs                                                                                                Practical Paediatrics Program
                                                                                                                                         The Practical Paediatrics Program
             ν    Which allergen/s should I request in suspected                                                               is an RACGP CPD-accredited upskilling program for GPs,
                  allergic rhinitis and/or allergic asthma?                                                                              provided through an alliance between
                                                                                                                                            Divisions of General Practice
             ν    When should I request an allergen “mix”?
                                                                                                                                         and the Royal Children’s Hospital,
             ν    When should I request total IgE?                                                                                           in partnership with Nicepak
                                                                                                                                                 (distributors of baby products, creams
             ν    How do I interpret specific IgE results in infants?                                                                                     and medications).
             ν    How do I interpret antibiotic specific IgE results?
             ν    How do I interpret bee venom sIgE results?                                                                               www.rch.org.au/kidsconnect
                                                                                                                                           (RCH Primary Care Liaison)
                                                                                                                                               tel (03) 9345 4645