6/17/2013

Celiac Disease Diagnosis and Follow-Up Karina Rodriguez-Capote MD, PhD, FCACB, Clinical Chemist, DynaLIFEDx

Learning Objectives 

To describe the clinical presentation, pathogenesis and laboratory work-up of celiac disease (CD)

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To recognize the diagnostic criteria

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To discuss the analytical principle and clinical utility of celiac disease antibody tests

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Celiac Disease Facts 

300,000 Canadians suffer from celiac disease

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1 in 133 people have celiac disease

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Occurs at any age, average time to diagnosis ~12 years

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Genetic factors HLA-DQ2, HLA-DQ8, other genes?

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Comorbidity with autoimmune and genetic diseases

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Classification spectrum gluten sensitivity  latent CD  CD  refractory CD

Canadian Celiac Association Gastroenterology 2009; 137:1912-1933

Viral infection Change in bacterial flora

Celiac Disease is an immune disorder triggered by the environment (gluten) in genetically susceptible individuals

Pathogenesis Gliadin gains access via transand para-cellular routes to the basal surface of the epithelium, and interact directly with the immune system resulting in the production of cytokines that cause tissue damage. This leads to villous atrophy and crypt hyperplasia, as well as the activation and expansion of B cells that produce antibodies. N Engl J Med 2007; 357:1731-1743

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The Celiac Iceberg Symptomatic Celiac Disease

Manifest mucosal lesion

Positive

Serology Hematological: iron deficiency anemia Digestive:, mouth ulcers, Silent Celiac unexplained increase of liver Disease enzymes and rare severe hepatopathy Normal Latent Celiac Disease Rheumatologic: demineralization, Mucosa arthralgias fractures Neurological: peripheral neuropathy, epilepsy ,ataxia Genetic susceptibility: - DQ2, DQ8 (vitamin E deficiency?), migraine Gynecological: infertility, amenorrhea, fetal hypotrophy, miscarriages Feldman: Sleisenger & Fordtran's Gastrointestinal and Liver Disease, 8th ed.

Diagnostic Tests  Screening tests  serum autoantibodies (IgA/IgG tTG, IgA/IgG EMA, IgA/IgG

antigliadin antibodies (AGA)  total IgA to assess for selective IgA deficiency nephelometry or immunoturbidimetry

 Confirmation test  small bowel biopsy • • •

villous atrophy lymphocytic infiltration enlarged hyperplastic crypts

 HLA-DQ molecular testing Biopsy Interpretation of the GIT Mucosa 2006 Elizabeth Montgomery 158-165.

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Screening Antibody Tests Tissue transglutaminase (anti-TTG)  ELISA  IgA anti-TTG test of choice for diagnosis and monitoring  Cost-effective, more sensitive than EMA

Anti-endomysial antibodies (EMA)  Immunofluorescence assay  Improved sensitivity, superior specificity  Expensive and difficult to standardize  High concordance rate with anti-tissue transglutaminase

American Journal of Gastroenterology 2010; 105:2520-2524, www.glutenpro.com

Screening Antibody Tests 

Anti-gliadin antibodies (AGA)     

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IgG or IgA anti-gliadin antibody tests ELISA Poor sensitivity and specificity No longer recommended due to high FP rate Gluten sensitivity?

Deamidated gliadin peptide (anti-DGP)  ELISA  Higher specificity than native gluten, expensive  Combo IgG/IgA DGP potential screen avoids total IgA

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Celiacsure point of care test American Journal of Gastroenterology 2010 105:2520-2524

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EliA Celikey IgA tTG Phadia Sandwich ELISA (U/mL) Fluorescence Substrate, stop solution Wash Enzyme-labelled conjugate

F

Wash Patient autoantibody binds to antigen Human recombinant antigen coated to well

[TTG]

Interpretation 10

Negative Weakly positive Positive

www.somagen.com, www.phadia.com

ImmuGlo IgG/IgA EMA Test (U of A Hospital) Substrate: smooth muscle monkey esophagus Patient serum antibodies Fluorescein-labeled anti-human Ig conjugate Fluorescence microscope Antibody titer determined by testing serial dilutions TAT = 2-4 weeks

Kit insert available from IMMCO Diagnostics website

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Serological Test Comparison AGA-IgG AGA-IgA EMA (IgA)(IgG) TTG (IgA) TTG (IgG)

Sensitivity % 69 – 85 75 – 90 85 – 98 90 – 98 < 70

Specificity % 73 – 90 82 – 95 97 – 100 94 – 97 94 – 97

Antigliadin antibodies (AGA) Antiendomysial antibodies (EMA) Anti-tissue transglutaminase antibodies (TTG)

Am J Gastroenterol 2001;96:3237-46

Celiac Testing in Edmonton  Confirmatory testing of all initial positive anti-tissue transglutaminase (ATTG) samples by the anti-endomysial test has been discontinued.  Anti-endomysial antibody (AENDO/ EMA) will automatically be done on:  patients < 2 years old when an ATTG is 2 years old and IgA is