What test can the AGACNP order to support the diagnosis of celiac disease in a patient with severe anemia and abdominal cramping?

Diagnosis of Celiac Disease in a Patient with Anemia and Abdominal Cramping

Immunoglobulin A (IgA) tissue transglutaminase (TTG) antibody testing is the preferred diagnostic test to support a diagnosis of celiac disease in this patient with severe anemia and abdominal cramping. 1, 2

Rationale for IgA TTG Testing

• IgA tissue transglutaminase antibody (tTG-IgA) is the primary recommended screening test for suspected celiac disease with high sensitivity (90-96%) and specificity (>95%) 2
• Testing must be performed while the patient is on a gluten-containing diet, as positive serologic results may resolve with gluten removal 2, 3
• The American College of Gastroenterology (ACG) specifically recommends IgA TTG antibody as the preferred test in persons older than two years 1

Clinical Presentation Supporting Celiac Disease

• The patient's presentation with severe anemia (Hgb 6.8) is a classic extraintestinal manifestation of celiac disease 3, 4
• Abdominal cramping is a common gastrointestinal symptom of celiac disease 3
• Fever and hypotension may represent complications of severe anemia and malabsorption 3

Diagnostic Algorithm

1. Order IgA tissue transglutaminase (TTG) antibody test 1, 2
2. Simultaneously measure total IgA level to rule out IgA deficiency which could affect interpretation 1, 3
3. Consider additional serologic testing with endomysial antibody (EMA) which has higher specificity (99.6%) 2, 5
4. Refer for upper endoscopy with small bowel biopsy (at least 6 specimens from second part of duodenum) as the gold standard for diagnosis 1, 2

Supporting Evidence Quality

The recommendation for IgA TTG testing is supported by multiple high-quality guidelines, including the American College of Gastroenterology (2014) 1, American Gastroenterological Association (2019) 1, and recent Praxis Medical Insights (2025) 2, 3. These guidelines consistently identify IgA TTG as the preferred initial test for celiac disease diagnosis.

Why Other Options Are Not Preferred

• Option A (Calcium, vitamin D, vitamin K, iron, folate, vitamin B12 levels): While these tests may identify nutritional deficiencies that commonly occur in celiac disease 3, they are not diagnostic for celiac disease itself and should be performed after establishing the diagnosis 3
• Option B (Unit of packed red blood cells): This addresses the anemia symptomatically but does not help establish the underlying diagnosis of celiac disease 3
• Option C (Gluten-free diet): Initiating a gluten-free diet before diagnostic testing can lead to false-negative results and should be avoided 1, 3

Common Pitfalls to Avoid

• Initiating a gluten-free diet before completing diagnostic testing can lead to false-negative results 1, 3
• Failing to test for IgA deficiency when performing celiac serology, as this can lead to false-negative results 1, 3
• Relying solely on serology without biopsy confirmation can lead to misdiagnosis 6
• Overlooking extraintestinal manifestations like severe anemia can delay diagnosis 3, 4

The combination of abdominal cramping and severe anemia strongly suggests celiac disease as a potential diagnosis, and IgA tissue transglutaminase testing is the most appropriate initial diagnostic test to confirm this suspicion.