From ACP Internist, volume 43 number 2 and ACP Weekly Internist, January 17, 2023

Improving celiac disease diagnosis

• Celiac disease should be part of the differential diagnosis for several clinical presentations:
o Chronic diarrhea or bloating.
o Weight loss.
o Features of malabsorption.
• Any patient with iron deficiency of unknown etiology should be screened for celiac disease.
• Consider the diagnosis in patients with unexplained early bone loss, unexplained infertility, abnormal liver enzymes and vitamin/mineral deficiencies.
• Fatigue and certain skin rashes should include celiac disease in the differential diagnosis.
• Approximately 20% of patients are completely asymptomatic.
• Patients at higher risk include those with type I diabetes, autoimmune thyroid disease, Down syndrome, or Turner syndrome.
• Individuals with rheumatoid arthritis, Sjögren disease and SLE are at moderately increased risk.
• Consider testing individuals with a first-degree family member with biopsy confirmed disease.
• The first step in the workup is antibody testing with a serum tissue transglutaminase antibody test as well as a serum IgA assay.
• If the patient has IgA deficiency, obtain a deamidated gliadin peptide IgG assay.
• In symptomatic adults unwilling or unable to undergo endoscopy, combination tissue transglutaminase antibody IgA (>10 times the ULN) with a positive endomysial antibody in a second blood sample are reliable tests for diagnosis of likely celiac disease
• An elevated level on antibody testing does not equate to a diagnosis of celiac disease but should lead to duodenal biopsy for definitive diagnosis.
• Consider a follow-up biopsy to assess mucosal healing in adults in the absence of symptoms after two years of starting a gluten-free diet.
• Symptom reduction or resolution on a gluten-free diet is not considered diagnostic. Some patients with non-celiac gluten sensitivity can improve on a gluten free diet.
• For patients who are already on a gluten-free diet genetic testing may help determine the likelihood of celiac disease. Human leukocyte antigen (HLA)-DQ2 or DQ8 are present in most patients with celiac disease.
• To determine if the gluten-free diet is having an effect, suggested that antibody testing be repeated at 4 to 6 months after diagnosis with additional testing at one year and then annually.
• It is also recommended that bone density be determined once a diagnosis is first made.
• Vaccination to prevent pneumococcal disease is suggested in patients with celiac disease.