Celiac

General Overview

  • Chronic GI disorder in which ingested gluten (protein in wheat, rye, barley) causes immune-mediated villous atrophy of the small intestine in genetically susceptible patients leading to malabsorption
    • Diagnosis confirmed by endoscopic small intestine biopsy (during a gluten-containing diet)
  • Clinical Spectrum
    • Classical
      • Malabsorption (diarrhea, steatorrhea, weight loss, growth failure)
    • Nonclassical
      • Absent signs of malabsorption but intestinal/extraintestinal symptoms
    • Subclinical (found on screening)
      • Below clinical detection but abnormal serological test and villous atrophy
    • Potential (latent)
      • Abnormal antibody but normal intestinal mucosa - may develop intestinal lesion (requires monitoring)
  • Treatment
    • Gluten-Free Diet (GFD)

Screen

  • Associated conditions at high risk
    • 1st degree relative celiac (5-20%)
    • DM1 (3-10%)
      • Consider serology screening q1-2y
    • Down syndrome
    • Turner syndrome
    • Autoimmune thyroid disease
    • Autoimmune liver disease
    • Selective IgA deficiency
  • Other features
    • Malabsorption
      • Abdominal pain/Bloating/Distension
      • Chronic diarrhea/Constipation/IBS
      • Weight loss/Fatigue
      • Iron deficiency anemia
      • Vit-D/Calcium - Dental enamel defects/Premature Osteoporosis
      • B12/Folate - Neurological symptoms (Peripheral neuropathy, ataxia, seizures)
    • Skin
      • Dermatitis Herpetiformis ("Celiac of the skin" - pruritic papulovesicular rash on extensor)
      • Recurrent aphthous stomatitis
    • Infertility
    • Abnormal LFTs
  • Additional features in children
    • Irritability
    • Recurrent vomiting
    • Delayed puberty
    • Growth failure/Short stature

Investigations

  • IgA tTG antibody (Sensitivity and Specificity 95%)
    • False-negative
      • Age<2yo
        • Consider in <2yo, screen with both IgA tTG and IgG DGP Ab
      • Lab error
      • Reduction/elimination of gluten (may be negative within weeks of GFD)
        • Gluten-containing diet should be resumed before ordering test
        • Consider HLA-DQ2/DQ8 for patients on a GFD
          • Note: HLA present in almost all patients with Celiac (95% DQ2, 5% DQ8)
      • Selective IgA deficiency
      • Immunosuppressed (eg. steroids)
      • Seronegative Celiac disease (rare) - if high suspicion, consider referral for small intestinal biopsy or HLA testing
  • Total IgA
    • If <0.2g/L, consider testing IgG DGP antibodies

Diagnosis

Important to differentiate between non-celiac gluten sensitivity to identify risk for nutritional deficiency, complications and evaluating risk to family members

  • Positive IgA tTG Ab requires endoscopic small intestinal biopsies to confirm
    • Do NOT start GFD prior to biopsy (as this will heal mucosa)
    • If GFD started, resume 3g gluten daily x 2-6w and referral to GI
  • Dermatitis herpetiformis
    • Skin biopsy can confirm (small intestinal biopsy not required)
  • In children can avoid biopsy with three criteria:
    • Positive tTG Ab >10x ULN
    • Positive endomysial Ab
    • Positive HLA-DQ2 or HLA-DQ8

Treatment

  • Strict Gluten-free diet (avoid wheat, barlet, rye - caution with oats)
    • Referral to dietician
    • Consider iron, folic acid, vitamin D and B12 testing
  • Consider TSH and liver transaminase q1-2y

Complications

  • Nutritional deficiency (anemia)
  • Osteoporosis
  • Growth failure
  • Autoimmune disorders (thyroid, liver)
  • Malignancy (GI, Lymphoma)