Coeliac disease is frequently misunderstood as a simple food allergy or a trendy dietary intolerance. In reality, it is a serious, systemic autoimmune condition triggered by the ingestion of gluten—a protein found in wheat, barley, and rye. In the UK, it affects approximately 1 in 100 people, yet an estimated 70% of those living with the condition remain undiagnosed.
The danger of undiagnosed Coeliac disease lies in its silent destruction. Every time a person with the condition consumes gluten, their immune system mounts an attack that damages the delicate lining of the small intestine. Over time, this damage severely impairs the body's ability to absorb essential nutrients, leading to a cascade of secondary health issues.
The Mechanism of Damage
The small intestine is lined with millions of tiny, finger-like projections called villi. These villi vastly increase the surface area of the gut, allowing for the efficient absorption of vitamins, minerals, and macronutrients into the bloodstream.
In Coeliac disease, the immune system mistakenly identifies gluten as a dangerous pathogen. It produces antibodies that attack the gluten, but in the process, they also attack the enzyme tissue transglutaminase (tTG) in the gut wall. This autoimmune crossfire blunts and flattens the villi (villous atrophy). The intestine becomes smooth, drastically reducing its ability to absorb nutrients, regardless of how healthy the patient's diet is.
A Spectrum of Symptoms
Historically, Coeliac disease was thought to primarily affect children, presenting with classic "textbook" symptoms: severe diarrhea, abdominal pain, and failure to thrive. Today, we know that the condition can develop at any age, and the symptoms are often entirely non-gastrointestinal.
Many adults present with "atypical" symptoms driven by the resulting malabsorption, including:
- Profound Fatigue: Often caused by secondary Iron Deficiency Anaemia or Vitamin B12 deficiency, as the damaged gut cannot absorb these nutrients.
- Neurological Issues: Brain fog, peripheral neuropathy (tingling in hands and feet), and frequent migraines.
- Bone Health: Early-onset osteopenia or osteoporosis due to the inability to absorb calcium and Vitamin D.
- Reproductive Issues: Unexplained infertility or recurrent miscarriages.
The Diagnostic Pathway: Why You Must Keep Eating Gluten
The most common mistake patients make when they suspect gluten is causing their symptoms is to immediately adopt a gluten-free diet. If you stop eating gluten before being tested, the blood tests will return a false negative. The immune system stops producing the antibodies when the trigger is removed.
The clinical diagnostic pathway involves two main steps:
- Serology (Blood Testing): The first-line screening is a blood test measuring specific autoimmune antibodies. The most sensitive and specific marker is Tissue Transglutaminase IgA (tTG-IgA). We also test for Endomysial Antibodies (EMA) and check total IgA levels to ensure the patient isn't IgA deficient (which would also cause a false negative).
- Endoscopy and Biopsy: If the blood tests are positive, a gastroenterologist will perform an endoscopy to take small tissue samples (biopsies) from the duodenum. A pathologist examines these under a microscope to confirm the presence of villous atrophy, providing the definitive diagnosis.
Once diagnosed, the only treatment is a strict, lifelong, 100% gluten-free diet. Even microscopic amounts of cross-contamination can trigger the autoimmune response and perpetuate intestinal damage. However, with strict adherence, the gut lining can heal, nutrient absorption is restored, and the long-term risks (including a slightly increased risk of certain intestinal lymphomas) are significantly reduced.
Test for Coeliac Disease at Home
Important: you must continue eating gluten daily for at least 6 weeks before testing — stopping gluten will cause a false negative result.
- Anaemia Profile Blood Test: Investigates iron, B12, and folate deficiencies caused by Coeliac-related malabsorption — useful alongside Coeliac antibody testing.
Medical References
- National Institute for Health and Care Excellence (NICE). (2015). Coeliac disease: recognition, assessment and management. NICE guideline [NG20].
- Ludvigsson, J. F., et al. (2014). Diagnosis and management of adult coeliac disease: guidelines from the British Society of Gastroenterology. Gut, 63(8), 1210-1228.
- Fasano, A., & Catassi, C. (2012). Clinical practice. Celiac disease. New England Journal of Medicine, 367(25), 2419-2426.