Celiac Disease

Essentials of Diagnosis

• Typical symptoms

  • Weight loss

  • Chronic diarrhea

  • Abdominal distention

  • Growth retardation

• Atypical symptoms

  • Dermatitis herpetiformis

  • Iron deficiency anemia

  • Osteoporosis

• Abnormal serologic test results

• Abnormal small bowel biopsy

• Clinical improvement on gluten-free diet

General Considerations

• Caused by an immunologic response to gluten that results in diffuse damage to the proximal small intestinal mucosa with malabsorption of nutrients

• Gluten is a storage protein found in certain grains that is partially digested in the intestinal lumen into glutamine-rich peptides

• Most cases present in childhood or adulthood, although symptoms may manifest between 6 and 24 months of age

Demographics

• Global prevalence is 1.4%

• In North America, the prevalence of biopsy-confirmed disease is 0.5%

Symptoms and Signs

• "Classic" symptoms of malabsorption more commonly present in infants (< 2 years)

  • Diarrhea

  • Steatorrhea

  • Weight loss

  • Abdominal distention

  • Weakness

  • Muscle wasting

  • Growth retardation

• Older children and adults are less likely to manifest signs of serious malabsorption but may report

  • Chronic diarrhea

  • Dyspepsia

  • Flatulence

  • Variable weight loss

• Many adults have minimal or no gastrointestinal symptoms but present with extraintestinal "atypical" manifestations

  • Fatigue

  • Depression

  • Iron-deficiency anemia

  • Osteoporosis

  • Short stature

  • Delayed puberty

  • Amenorrhea or reduced fertility

• Physical examination

  • In mild cases: may be normal

  • In more severe cases: may reveal signs of malabsorption, loss of muscle mass or subcutaneous fat, pallor, easy bruising, hyperkeratosis, or bone pain

• Abdominal examination may reveal distention with hyperactive bowel sounds

• Dermatitis herpetiformis in < 10%

Differential Diagnosis

• Irritable bowel syndrome

• Malabsorption due to other causes

• Lactase deficiency

• Viral gastroenteritis

• Eosinophilic gastroenteritis

• Whipple disease

• Giardiasis

• Mucosal damage caused by acid hypersecretion associated with gastrinoma

• Non-celiac gluten sensitivity

  • Frequency and cause of this entity is debated

  • A large 2013 study found that symptoms improved in gluten-sensitive patients when placed on a FODMAP-restricted diet and worsened to similar degrees when challenged in a double-blind crossover trial with gluten or whey proteins

  • A 2018 double-blind crossover trial in patients self-reporting gluten sensitivity found significantly higher symptom scores during the fructan challenge than during gluten or placebo challenges

  • Finally, a 2019 randomized trial conducted in healthy volunteers found no difference in gastrointestinal symptoms between those given diets with gluten supplements versus placebo

  • These data suggest that self-reported wheat sensitivity is not due to gluten intolerance and that the symptom improvement reported by patients with gluten restriction is due to broader FODMAP elimination

Laboratory Tests

• Obtain complete blood count, prothrombin time, serum albumin, iron or ferritin, calcium, alkaline phosphatase, red cell folate, vitamins B₁₂, A, and D levels

• Iron deficiency or megaloblastic anemia occurs because of iron or folate or vitamin B₁₂ malabsorption

• Elevation of prothrombin time occurs due to vitamin K deficiency

• Other deficiencies may include zinc and vitamin B₆

• Serologic tests should be performed in all patients

  • IgA transglutaminase-2 (IgA TG2) antibody is recommended; has a 98% sensitivity and 98% specificity for detecting celiac disease

  • Antigliadin antibodies are not recommended because of their lower sensitivity and specificity

  • IgA antiendomysial antibodies are less preferred due to the lack of standardization among laboratories

  • A serum IgA level should be obtained in patients with a negative IgA TG2 antibody when celiac disease is strongly suspected because up to 3% of patients with celiac disease have IgA deficiency

  • A test that measures IgG antibodies to deamidated gliadin peptides (anti-DGP) has excellent sensitivity and specificity and is useful in patients with IgA deficiency and in young children

  • HLA-DQ2/DQ8 testing is sometimes performed in selected cases of diagnostic uncertainty (eg, in patients who initiated a gluten-free diet prior to establishing a formal diagnosis): negative DQ2/DQ8 genotyping excludes the diagnosis

• Serologic tests become negative (undetectable) 3–12 months after dietary gluten withdrawal

Imaging

• Dual-energy x-ray densitometry scanning for osteoporosis

Diagnostic Procedures

• Mucosal biopsy: endoscopic mucosal biopsy of the proximal duodenum (bulb) or distal duodenum confirms diagnosis

• Remove all gluten from the diet

• Most patients with celiac disease also have lactose intolerance either temporarily or permanently and should avoid dairy products until the intestinal symptoms have improved on the gluten-free diet

• Patients who have acute severe diarrhea with dehydration, electrolyte imbalance, and malnutrition may require total parenteral nutrition and intravenous or oral corticosteroids (prednisone 40 mg or budesonide 9 mg) for 2 or more weeks as a gluten-free diet is initiated

Medications

• Nutrient supplements in initial stages of therapy, as necessary

  • Folate

  • Iron

  • Zinc

  • Calcium

  • Vitamins A, B₆, B₁₂, D, and E

• Calcium, vitamin D, and bisphosphonate therapy for osteoporosis

• Corticosteroids or immunosuppression with azathioprine or cyclosporine may be helpful in patients with refractory celiac disease who do not have intestinal T cell lymphoma

Follow-Up

• Improvement in symptoms is anticipated within a few weeks on the gluten-free diet

Prognosis

• Excellent prognosis with appropriate diagnosis and treatment

• Celiac disease that is truly refractory to gluten withdrawal occurs in < 5% and carries a poor prognosis