Celiac Disease

Key Points

Celiac Disease in Children and Adolescents

Recent guidelines from the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) discuss serology testing for the evaluation of celiac disease (CD) and suggest when HLA-DQ2/HLA-DQ8 typing is recommended.

Recommendations for Celiac Disease (CD) Testing in Children and Adolescents (ESPGHAN 2012)*

ESPGHAN recommends testing for CD in children and adolescents

  • With unexplained
    • Gastroenterological symptoms
    • Poor growth
    • Delayed puberty
    • Iron deficiency anemia 
    • Abnormal liver testing
  • In the presence of the following risks for CD (even if asymptomatic)

Laboratory Testing Options

Recommended antibody tests

*Individual must be on gluten-containing diet when tested and IgA status must be known

  • Tissue transglutaminase (tTG) or endomysial antibody (EMA) IgA testing – both tests highly sensitive
  • In children <2 years with high suspicion of CD – further testing may increase sensitivity if tTG and/or EMA IgA is negative
    • Consider anti-deamidated gliadin peptide (DGP) antibody test
  • Anti-gliadin antibody (AGA) testing is not useful

HLA genotyping

  • Should not be routinely performed
  • Lack of HLA-DQ2/HLA-DQ8 virtually excludes CD
  • Uses
    • Strong serologic evidence and clinical suspicion AND the desire is to avoid small bowel biopsy
    • Negative CD specific antibodies with mild changes on proximal small intestinal biopsy

Available recommended ARUP tests

  • Celiac Disease Reflexive Cascade 2008114  (includes IgA, dual antigen screen, tTG IgA/IgG, DGP IgA/IgG, and endomysial antibodies IgA)
  • Individual IgA tests for IgA-competent individuals
    • Tissue Transglutaminase Antibody, IgA 0097709
    • Endomysial Antibody, IgA by IFA 0050736
    • Deamidated Gliadin Peptide (DGP) Antibody, IgA 0051357
    • Celiac Disease Dual Antigen Screen with Reflex 2002026
    • Celiac Disease Dual Antigen Screen 0051689
  • Individual IgG tests for IgA-deficient individuals

    • Tissue Transglutaminase Antibody, IgG 0056009  
    • Endomysial Antibody, IgG 2005501  
    • Deamidated Gliadin Peptide (DGP) Antibody, IgG 0051359
    • Celiac Disease Dual Antigen Screen with Reflex 2002026
    • Celiac Disease Dual Antigen Screen 0051689
  • Celiac Disease (HLA-DQA1*05, HLA-DQB1*02, and HLA-DQB1*03:02) Genotyping 2005018  
*Husby S et al. European Society for Pediatric Gastroenterology, Hepatology, and Nutrition guidelines for the diagnosis of coeliac disease. J Pediatr Gastroenterol Nutr. 2012 Jan;54(1):136-60

Diagnosis

Indications for Testing

Criteria for Diagnosis

  • Positive tTG IgA and/or EMA IgA serologic test with biopsy consistent with CD in individuals with normal serum IgA levels
    • CD may be confirmed without the need for biopsy in symptomatic individuals with high levels of CD-specific antibodies and who are HLA-DQ2/DQ8 positive
  • Complete resolution of clinical symptoms and/or a seronegative response following a gluten-free diet
    • Gluten rechallenge not necessary except in patients who had no initial biopsy or an uncharacteristic biopsy

Laboratory Testing

  • Celiac disease tests and characteristics
    TestCharacteristicsLimitations
    Celiac Disease Reflexive Cascade (includes IgA, dual antigen screen, tTG IgA/IgG, DGP IgA/IgG, and endomysial antibodies)

    Preferred reflexive screening cascade for celiac disease (CD) diagnosis

    Begins with IgA; depending on findings, one or more reflexive tests may be added for clinical interpretation

    • Tissue transglutaminase antibody, IgA
    • Tissue transglutaminase antibody, IgG
    • Endomysial antibody, IgA by IFA
    • Deamidated gliadin peptide (DG) antibody, IgA
    • Deamidated gliadin peptide (DGP) antibody, IgG
    • Celiac disease dual antigen screen
     
    Celiac Dual Antigen Screen with Reflex (includes tTG IgA/IgG by ELISA; DGP IgA/IgG by ELISA)Acceptable reflexive screening test for CD

    More expensive than tTG testing

    Tissue Transglutaminase Antibody (tTG) IgA/IgG by ELISA

    Preferred single initial screen for CD due to increased sensitivity, lack of subjectivity

    Confirmation by endomysial antibody (EMA) may be necessary for low to moderate levels of tTG antibody results

    Testing for deamidated gliadin peptide (DGP) antibodies may also increase sensitivity for CD, particularly in children <2 years

    May be less reliable in children <2 years

    tTG antibodies may be present despite undetectable levels of IgA

    Deamidated Gliadin Peptide (DGP) IgA/IgG by ELISA

    Not a recommended first line test for CD

    May be considered in children <2 years if tTG or EMA negative

    Higher sensitivity/specificity than conventional antigliadin antibody (AGA) tests

    May be present in the absence of  tTG IgA antibodies
    Endomysial Antibody (EMA) IgA/IgG by IFA

    Acceptable screen for CD

    High clinical specificity with good positive predictive value for active CD

    Testing for DGP antibodies may improve diagnostic sensitivity in children <2 years; may be used as an alternate to EMA to confirm low to moderate tTG antibody results

    More labor intensive  and expensive than tTG IgG testing
  • Initial testing
    • Serum IgA level by nephelometry – for determination of IgA levels prior to antibody testing (recommended); if patient is IgA deficient, all serologic testing must be performed with IgG tests to prevent false-negative antibody results
      • IgA level ≥7.0 mg/dL but below age-matched range – order Celiac Dual Antigen Screen with Reflex (see table above for components and characteristics)
        • Celiac Dual Antigen Screen with Reflex Test Results
          Celiac Dual Antigen Screen with Reflex Test Results
          NormalCeliac disease unlikely
          Positive or equivocalConsider HLA genotyping (refer to Genetic Testing section)
      • IgA <7.0 mg/dL – order tTG IgG and DGP IgG
        • Consider evaluation for immunoglobulin deficiency if IgG is normal – IgA deficiency may accompany other immunoglobulin deficiencies
        • Note: infants may present with transient suboptimal levels of IgA and/or IgG levels, which may not be related to immune deficiency
        • tTG IgG and DGP IgG Test Results
          tTG IgG and DGP IgG Test Results
          NormalCeliac disease unlikely
          Positive or equivocalConsider HLA genotyping (refer to Genetic Testing section)
      • IgA level normal (age-matched range) – order tTG IgA
        • tTG IgA Test Results
          tTG IgA Test Results
          High-positive tTG (IgA ≥100 U)Celiac disease (CD) likely; consider HLA genotyping (see Genetic testing)
          Weak-moderate positive tTG IgA (20-99 U)Order EMA IgA by IFA, DGP IgA, HLA genotyping
          • EMA and/or DGP negative; HLA positive
          Perform biopsy (see Histology section)
          • EMA and/or DGP positive, HLA negative
          Likely false-negative HLA genotyping test; consider biopsy to confirm or rule out CD
          • EMA and/or DGP positive, HLA positive
          CD confirmed
          • EMA and DGP negative; HLA negative
          Likely false-positive anti-tTG test
          Negative tTG IgA (<19 U)

          CD unlikely

          Exclude history of gluten-free diet or immunosuppressants (causes false-positive results)

          Consider HLA genotyping (in light of age and associated diseases) – refer to Genetic Testing section

  • Genetic testing – HLA genotyping
    • HLA-DQ2 (HLA-DQA1*05 and HLA-DQB1*02) and HLA-DQ8 (HLA-DQB1*03:02)
      • HLA-DQ2 is positive in 90-95% of patients; presence does not confirm CD
      • Found in 30-40% of general population
      • Absence virtually excludes CD
      • Not necessary for routine laboratory evaluation of CD because of its low positive predictive value
      • May be indicated in individuals at risk for CD or individuals who are repeatedly seropositive but biopsy-negative
      • Wheat allergy testing – do not order because it is not relevant
    • Results
      • HLA positive – CD confirmed
        • Not necessary to confirm by biopsy; may consider biopsy for atypical presentation
      • HLA negative – likely false-positive tTG test
  • Other testing
    • F-actin IgA antibody by ELISA
      • Presence of anti-actin antibodies in biopsy-confirmed CD patients may indicate intestinal villus atrophy – more severe form of disease expected
      • Should be ordered only in patients with confirmed CD by biopsy

Histology

  • Duodenal biopsy – gold standard for CD diagnosis
    • 4-5 samples should be taken to increase probability
    • Patient should not be on a gluten-free diet at time of biopsy
    • Intestinal damage is assessed by a modified Marsh score
      • Scores range from 0, 1, 2, 3a to 3c
      • Marsh 0-1
        • Consider early phase disease
        • Follow-up testing on normal diet
        • Consider false-positive results
      • Marsh ≥2
        • CD confirmed

Prognosis

  • Anti-actin IgA (F-actin) levels correlate with severity of mucosa damage and may indicate moderate to severe disease

Differential Diagnosis

  • Irritable bowel syndrome (IBS)
  • Inflammatory bowel disease
  • Malabsorption
  • Malnutrition
  • Colorectal cancer
  • Lactose intolerance
  • Microscopic colitis
  • Other carbohydrate intolerance
  • Eosinophilic gastroenteritis
  • Infectious – Giardia
  • Intestinal lymphoma
  • Pancreatic insufficiency
  • Common variable immune deficiency
  • Autoimmune enteropathy
  • IgA deficiency

Screening

  • Serologic and/or genetic (HLA-DQ2 and HLA-DQ8) screening is not recommended for the general population

  • Serologic screening for celiac disease (CD) is recommended for specific at-risk groups, including first degree relatives of CD patients and individuals with the following
  • For asymptomatic at-risk children (groups referred to above) screening  should begin after 2 years and when child has been on wheat diet for ≥1 year or with suggestive signs and symptoms
  • HLA-DQ2 and HLA-DQ8 testing is recommended mostly for exclusion when diagnostic and biopsy results are equivocal  
    • In rare cases, some patients with CD have been reported to have only DQA1*05 or DQB1*02, the latter usually associated with HLA-DR7 heterozygosity or homozygosity

Monitoring

  • Monitoring adherence to gluten-free diet (GFD) or disease activity is part of American Gastroenterological Association (AGA) guidelines
    • tTG and/or DGP IgA or IgG assay, EMA assay
      • Either tTG, DGP, or EMA assays can be used depending on previous results in monitoring adherence to GFD
      • Assay should be chosen (IgA or IgG) based on IgA levels
      • Decline in antibody levels may correlate with normalization of the intestinal villi
      • Typically ordered every 3-6 months – if levels remain elevated after >12 months of GFD, consider rebiopsy
    • F-actin IgA antibody
      • Strict adherence to GFD and normalization of the intestinal villi correlate with declining levels of F-actin IgA antibodies in some patients with celiac disease

Clinical Background

Celiac disease (CD), or gluten sensitive enteropathy, is a nonallergic, immune-mediated sensitivity in genetically susceptible individuals to gluten in wheat or related proteins found in barley and rye.

Epidemiology

  • Incidence – 1/133 in U.S.
  • Age – three defined peaks
    • Infancy
    • Second to third decade of life
    • Fifth to sixth decade of life
  • Ethnicity – mainly affects Caucasians of European origin

Genetics

  • HLA-DQ2 (HLA-DQA1*05 and HLA-DQB1*02) – 90-95% of CD patients have HLA-DQ2
  • HLA-DQ8 (HLA-DQB1*03:02) – 5-10% of CD patients have HLA-DQ8
  • 75-90% concordance in monozygotic twins; 10-20% in dizygotic twins

Risk Factors

Pathophysiology

  • T-cell mediated inflammatory response in proximal small bowel
    • Celiac lesion may be characterized by increased intraepithelial lymphocytes with crypt hyperplasia and partial, subtotal, or total atrophy
  • tTG (tissue transglutaminase) has been identified as the major target autoantigen of the endomysial antibody (EMA)
    • tTG is an enzyme that catalyzes the replacement of amide groups of protein and peptide-bound glutamine residues by primary amines (cross-linking) as well as by hydrolysis (deamidation)
  • Gliadin, a glutamine-rich protein, has been identified as a specific substrate for tTG
    • Deamidation of gliadin has been reported to improve the overall diagnostic performance of conventional antigliadin antibody assays

Clinical Presentation

  • Clinical presentation – extremely varied and tends to differ by age group
    • General symptoms – anemia, fatigue, weight loss
    • Pediatric symptoms – diarrhea, abdominal distention, malnutrition
      • Symptoms of malnutrition include the following
    • Adult symptoms
      • Intestinal symptoms
        • Abdominal pain
        • Flatulence
        • Diarrhea
        • Steatorrhea in severe cases
      • Extraintestinal symptoms
        • Anemia 
        • Fatigue and malaise – may occur independently of anemia
        • Neurologic or psychiatric disorders – epilepsy, depression, migraines
        • Neuromuscular abnormalities – osteoporosis, osteopenia, joint pain/inflammation
        • Infertility/recurrent fetal loss
        • Mouth ulcers/dermatitis herpetiformis
  • Associated conditions

Treatment

  • Gluten-free diet may control celiac disease/gluten sensitive enteropathy and associated risks
    • Positive predictive value of benefits of gluten-free diet <40%
    • Response does not equate to disease being present
    • Gluten-free diet removes other components that make symptoms worse in IBD, functional dyspepsia, or gastroesophageal reflux disease
  • American Gastroenterological Association (AGA) recommends lifelong adherence to gluten-free diet if celiac confirmed
  • 5% are true nonresponders to diet (refractory celiac disease)
    • Consider immunosuppressive therapy to reduce risk of lymphoma

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Celiac Disease Reflexive Cascade 2008114
Method: Quantitative Nephelometry/Semi-Quantitative Enzyme-Linked Immunosorbent Assay//Semi-Quantitative Indirect Fluorescent Antibody

Preferred reflexive screening cascade for CD diagnosis (includes IgA, dual antigen screen, tTG IgG and IgA antibodies, endomysial antibodies (EMA) IgA, and DGP antibodies)

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

Panel not recommended for follow-up testing in confirmed celiac patients

Antigliadin antibodies may be found in healthy individuals as well as individuals with other inflammatory bowel conditions

 
Tissue Transglutaminase (tTG) Antibody, IgA 0097709
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Preferred screen for suspected celiac disease (CD) in IgA-competent individuals

Useful in monitoring compliance with gluten free diet (GFD)

Certain individuals, particularly children <2 years, may test negative for tTG IgA antibodies

Not recommended for individuals with suboptimal IgA or IgA deficiency

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

 
Tissue Transglutaminase Antibody, IgG 0056009
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Preferred screen for suspected CD in IgA-deficient individuals

Useful in monitoring compliance with gluten free diet (GFD)

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

Certain individuals, particularly children <2 years who test negative for tTG and/or EMA antibodies, may be positive for DGP IgA and/or IgG antibodies

 
Deamidated Gliadin Peptide (DGP) Antibody, IgA 0051357
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Acceptable screen for suspected CD in IgA-competent individuals

May be useful in diagnosing children <2 years who test negative for tTG and EMA antibodies

Useful in monitoring compliance of GFD

Certain individuals, particularly children <2 years who test negative for tTG and/or EMA antibodies, may be positive for DGP IgA and/or IgG antibodies

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

 
Deamidated Gliadin Peptide (DGP) Antibody, IgG 0051359
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Acceptable screen for suspected CD in IgA-deficient individuals

May be useful in diagnosing children <2 years who test negative for tTG and EMA antibodies

Useful in monitoring compliance of GFD

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

Certain individuals, particularly children <2 years who test negative for tTG and/or EMA antibodies, may be positive for DGP IgA and/or IgG antibodies

 
Endomysial Antibody, IgA by IFA 0050736
Method: Semi-Quantitative Indirect Fluorescent Antibody

Acceptable single screening test for CD in IgA-competent individuals

Acceptable follow-up test for weak positive or negative tTG IgA screen

May aid in monitoring compliance of GFD

More labor intensive than tTG IgA testing

Moderate sensitivity in active disease

 
Endomysial Antibody, IgG 2005501
Method: Semi-Quantitative Indirect Fluorescent Antibody

Acceptable single screening test for CD in IgA-deficient individuals

Acceptable follow-up test for weak positive or negative tTG IgG screen

May aid in monitoring compliance of GFD

More labor intensive than tTG IgG testing

 
Celiac Disease Dual Antigen Screen with Reflex 2002026
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Acceptable reflexive screening test for CD

Panel includes CD dual-antigen screen; tTG antibodies IgA and IgG; and DGP antibodies IgA and IgG

Positive screen reflexes to IgA antibody testing for tTG and DGP; negative screen reflexes to IgG antibody testing for tTG and DGP

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

 
Celiac Disease Dual Antigen Screen 0051689
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Acceptable screening test for CD

Panel includes CD dual-antigen screen; tTG and DGP antibodies, IgA and IgG

Test results alone are not diagnostic; biopsy necessary for a diagnosis of CD/gluten sensitive enteropathy

If positive, individual tTG and DGP antibody assays must be performed

F-Actin (Smooth Muscle) Antibody, IgA 0051724
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Do not use to screen for CD

May be used to estimate severity of intestinal villous atrophy in confirmed CD

Does not replace intestinal biopsy for confirming CD

 
Celiac Disease (HLA-DQA1*05, HLA-DQB1*02, and HLA-DQB1*03:02) Genotyping 2005018
Method: Polymerase Chain Reaction/Fluorescence Monitoring

Do not use in initial evaluation of CD

Use for symptomatic individuals with

  • Borderline celiac-associated antibody test results (transglutaminase and/or endomysial antibodies)
  • Ambiguous small bowel biopsy results
  • Symptoms despite a gluten-free diet
  • Regression of symptoms on a gluten-free diet, but individual refuses to discontinue diet for testing

Clinical sensitivity/specificity – 100%/3%

Analytical sensitivity/specificity – >99%

Negative predictive value – 100%

Other HLA types will not be detected

Rare diagnostic errors can occur due to probe-site mutations

 
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Reticulin Antibody, IgA with Reflex to Titer 0050698
Method: Semi-Quantitative Indirect Fluorescent Antibody
Not recommended for CD testing; use tTG testing
Immunoglobulin A 0050340
Method: Quantitative Nephelometry

IgA results determine whether to use IgA or IgG tTG and DGP assays

Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, IgA by IFA 0050734
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Indirect Fluorescent Antibody

Screen for CD in individuals who are not IgA deficient

Certain individuals, particularly children <2 years who test negative for tTG and/or EMA antibodies, may be positive for DGP IgA and/or IgG antibodies

tTG IgA and EMA IgA have equivalent diagnostic utility for CD

Deamidated Gliadin Peptide (DGP) Antibodies, IgA and IgG 0051358
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Certain individuals, particularly children <2 years who test negative for tTG and/or EMA antibodies, may be positive for DGP IgA and/or IgG antibodies

Test results alone are not diagnostic; biopsy recommended for a diagnosis of CD/gluten sensitive enteropathy