Celiac disease and iron deficiency

The review by Sholzberg and colleagues¹ provides clear and practical recommendations that will help clinicians recognize and treat iron deficiency more effectively. However, an important gap in their recommendations is celiac disease testing in patients with iron deficiency.

International gastroenterology guidelines consistently highlight the importance of celiac disease testing in this patient population. The American Gastroenterological Association recommends that adults with iron-deficiency anemia and a plausible risk of celiac disease undergo serologic testing, with small bowel biopsy if serology is positive.² The British Society of Gastroenterology goes further, recommending that all adults with confirmed iron-deficiency anemia should be tested for celiac disease, using serology or at the time of gastroscopy.³ Tissue transglutaminase immunoglobulin A (tTG IgA) testing has excellent diagnostic accuracy for untreated celiac disease, with a sensitivity of about 95% and a specificity greater than 95%.⁴ Immunoglobulin A deficiency is more common in patients with celiac disease and should be excluded if tTG IgA testing is used.⁵

The importance of testing for celiac disease is not trivial. Celiac disease affects about 1% of the population, yet 70% of cases remain undiagnosed because symptoms are often nonspecific or extraintestinal. It is more common in females and often presents with iron-deficiency anemia, a common extraintestinal manifestation, which can improve with a gluten-free diet alone.⁵ A meta-analysis showed that 3% to 6% of patients with iron-deficiency anemia will be diagnosed with biopsy-confirmed celiac disease.⁶ Beyond anemia, untreated celiac disease is associated with serious complications, including osteoporosis, infertility, and increased risk of enteropathy-associated T-cell lymphoma.⁵ Identification of patients with celiac disease facilitates timely initiation of a gluten-free diet, prevention of recurrent anemia, and surveillance for long-term and systemic complications.

Including evidence-based Canadian recommendations on celiac disease testing in iron deficiency would harmonize practice with international standards and help reduce delayed or missed diagnoses. Improving implementation of this important testing strategy for clinicians could increase the detection of this common diagnosis, optimize patient management, and improve long-term prognoses.