From the Guidelines
Investigation for celiac disease should begin with serological testing, specifically anti-type 2 transglutaminase (TG2) antibodies, as it has high sensitivity (93%) and specificity (98%) 1.
Key Steps in Investigation
- Serological testing should be performed while the patient is on a gluten-containing diet to avoid false negative results.
- If serological testing is positive, the next step is an upper endoscopy with multiple duodenal biopsies (at least 4-6 samples) to confirm the diagnosis by showing characteristic histological changes such as villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes.
- Genetic testing for HLA-DQ2 and HLA-DQ8 haplotypes can be useful in certain situations, particularly to rule out celiac disease in ambiguous cases, as nearly all celiac patients carry at least one of these genetic markers 1.
Importance of Early Diagnosis
Early diagnosis and initiation of a gluten-free diet can significantly improve the quality of life and reduce the risk of complications associated with celiac disease, such as malabsorption, osteoporosis, and increased risk of certain cancers 1.
Recent Guidelines
Recent guidelines from the American College of Gastroenterology (ACG) recommend that all diagnostic serologic testing for celiac disease should be performed before a gluten-free diet is initiated, and that IgA anti-tissue transglutaminase (TTG) antibody is the preferred test in persons older than two years 1.
Considerations
It is crucial to consider the patient's dietary status at the time of biopsy, as a gluten-reduced diet may reduce the severity of the lesion and impact pathologic interpretation 1.
Nutritional Deficiencies
After diagnosis, patients should be evaluated for nutritional deficiencies including iron, folate, vitamin B12, vitamin D, and calcium, as malabsorption is common in celiac disease 1.
From the Research
Investigation for Celiac Disease
- Celiac disease is a chronic small bowel disorder caused by an abnormal immune response to gluten in genetically susceptible individuals 2.
- The diagnosis of celiac disease typically involves serological tests, such as anti-endomyseal, anti-tissue transglutaminase, and anti-deamidated gliadin peptide antibodies, as well as duodenal biopsies 3.
Serological Tests
- Anti-tissue transglutaminase (tTG) and anti-endomysial (EMA) antibodies are highly sensitive and specific for celiac disease, with values exceeding 95% in most studies 4, 5.
- However, the sensitivity of these tests can be lower in patients with persistent villous atrophy despite a gluten-free diet, with sensitivity values below 50% 6.
- The specificity of tTG and EMA antibodies is generally high, with values ranging from 83% to 91% 6.
Diagnostic Algorithms
- Current diagnostic algorithms for adult celiac disease still rely on duodenal biopsies to confirm the diagnosis, although serological tests have excellent performance characteristics 3.
- A 'biopsy avoidance strategy' has been implemented in pediatric celiac disease, and future studies may inform whether this approach can be implemented in adult gastroenterology services 3.