Celiac disease

Celiac disease is an immune-mediated disorder in which gluten exposure damages the small intestine of a genetically predisposed person. Gluten-derived peptides, especially from wheat, barley, and rye, activate immune responses that flatten intestinal villi and increase inflammatory cell activity.¹ The resulting loss of absorptive surface can produce deficiencies of iron, folate, vitamin B12, calcium, and other nutrients.

Most affected people carry HLA-DQ2 or HLA-DQ8, but these genetic markers are common and do not establish the diagnosis; their absence makes celiac disease very unlikely.³ The condition may begin in childhood or adulthood and can occur in people with type 1 diabetes, autoimmune thyroid disease, Down syndrome, or a family history of celiac disease. It is distinct from wheat allergy and non-celiac gluten sensitivity.

Symptoms range from chronic diarrhea, bloating, abdominal pain, weight loss, and fatigue to problems outside the intestine. Iron-deficiency anemia, reduced bone density, infertility, recurrent mouth ulcers, peripheral neuropathy, and itchy blistering skin lesions called dermatitis herpetiformis may be presenting features.² Some people have little or no noticeable illness despite intestinal damage.

Initial testing usually measures IgA tissue transglutaminase antibodies, often with total IgA to identify selective IgA deficiency; an IgG-based test can be used when IgA is deficient.¹ Testing should occur while the person is consuming gluten, because gluten avoidance can produce misleadingly negative results. In adults, diagnosis commonly requires upper endoscopy with multiple duodenal biopsies, interpreted alongside serology and clinical findings. HLA-DQ2 or HLA-DQ8 testing is most useful for ruling out disease in selected uncertain cases.

A strict, lifelong gluten-free diet is the established treatment for celiac disease. Removing wheat, barley, and rye usually allows symptoms to improve and the intestinal lining to recover, although healing may take months or longer, particularly in adults.⁴ Patients generally benefit from a dietitian who can identify hidden gluten, assess nutritional intake, and help maintain a balanced diet rather than relying on highly processed gluten-free substitutes.

Follow-up commonly includes symptom review, nutritional assessment, and repeat celiac serology; persistent positive antibodies or symptoms may indicate continuing exposure, an incorrect diagnosis, another disorder, or rarely refractory celiac disease.² Clinicians may assess iron, folate, vitamin B12, vitamin D, calcium, and bone health according to age, severity, and risk. Gluten-free labeling and prevention of cross-contact are especially important in shared kitchens and food-service settings.

Celiac disease has important edge cases that complicate both recognition and management. Dermatitis herpetiformis is its characteristic skin manifestation and may occur with minimal intestinal symptoms; the rash is associated with gluten sensitivity and usually requires a gluten-free diet, while dapsone can control skin symptoms under medical supervision.³ Selective IgA deficiency is more frequent in people with celiac disease and can make the most familiar antibody test falsely negative.

Pure oats are naturally gluten-free, but commercial oats may be contaminated during cultivation, transport, or processing; some people with celiac disease also react to avenin, an oat protein. Gluten-free communion wafers and medicines can pose practical challenges, and accidental exposure may be difficult to detect because symptoms are not always immediate. Rarely, persistent malabsorption despite a verified diet represents refractory celiac disease, a serious condition requiring specialist evaluation rather than simply stricter self-imposed restriction.⁵

Gluten

A group of storage proteins in wheat, barley, and rye that triggers the immune response in celiac disease.

Villi

Finger-like projections lining the small intestine that increase the surface available for nutrient absorption.

Tissue transglutaminase

An enzyme targeted by the principal blood antibody test used to screen for celiac disease.

Dermatitis herpetiformis

An intensely itchy blistering skin disease associated with celiac disease and gluten sensitivity.

Refractory celiac disease

Persistent or recurrent intestinal disease despite a strict gluten-free diet and exclusion of other causes.