Diagnosis & Marsh Classification
Understanding testing and damage classification
In One Minute
Coeliac disease diagnosis involves blood tests for specific antibodies, followed by an endoscopic biopsy of the small intestine. The Marsh classification system (Modified Marsh stages 0-4) categorizes the degree of intestinal damage, from normal villi to complete villous atrophy. Accurate diagnosis requires consuming gluten before testing—never start a gluten-free diet before being tested.
Diagnostic Process
Blood Tests
Screening for specific antibodies including tTG-IgA, EMA, and total serum IgA. These tests must be done while on a gluten-containing diet.
Endoscopy & Biopsy
If blood tests are positive, an upper endoscopy with small intestinal biopsy is performed to confirm diagnosis and assess damage.
Genetic Testing
HLA-DQ2 and HLA-DQ8 genetic testing can help rule out coeliac disease but cannot confirm it on its own.
The Marsh Classification System
The Marsh classification (modified by Oberhuber) is used to categorize the degree of damage to the small intestine based on biopsy results:
Marsh 0 - Normal
Normal intestinal architecture with no significant changes.
Marsh 1 - Infiltrative
Increased intraepithelial lymphocytes (IELs) with normal villi and crypts.
Marsh 2 - Hyperplastic
Increased IELs with crypt hyperplasia, but villi still present.
Marsh 3 - Destructive
Villous atrophy ranging from partial (3a) to subtotal (3b) to total (3c), along with crypt hyperplasia.
Marsh 4 - Hypoplastic
Total villous atrophy with crypt hypoplasia, representing severe and prolonged damage.
Understanding Diagnostic Delay
Many people with coeliac disease experience symptoms for years before receiving a diagnosis. Research indicates an average diagnostic delay of approximately 13 years from symptom onset to confirmation. This extended timeframe is not a measure of individual experience, but a reflection of systemic challenges in recognizing a condition that can present in many different ways.
Why Diagnostic Delay Occurs
Low Testing Rates
Despite the availability of reliable screening methods, coeliac disease testing is not routinely performed in many clinical settings unless symptoms are strongly suggestive. This results in missed opportunities for early detection, particularly in populations where the condition is underestimated or misunderstood.
Symptom Overlap with Other Conditions
Coeliac disease shares symptoms with more than 200 other conditions, including irritable bowel syndrome, chronic fatigue, anaemia, and anxiety disorders. This overlap often leads to alternative diagnoses that address symptoms but not the underlying autoimmune process. The conditions diagnosed during this period are frequently consequences or correlations of untreated coeliac disease rather than separate root causes.
Non Classical Presentations
While digestive symptoms are commonly associated with coeliac disease, many individuals present with non gastrointestinal manifestations such as skin conditions, neurological symptoms, joint pain, or reproductive issues. These less recognised presentations can lead clinicians to investigate other diagnostic pathways before considering coeliac disease.
Fragmented Healthcare Pathways
Individuals with diverse symptoms may consult multiple specialists across different medical domains. Without a coordinated approach or a clinical prompt to test for coeliac disease, the condition may remain outside the diagnostic focus even when symptoms persist across consultations.
Underrecognition in Adults
Coeliac disease is increasingly recognised as a condition that can develop at any age, yet diagnostic awareness remains higher in paediatric settings. Adults presenting with new or worsening symptoms may not be evaluated for coeliac disease as readily, contributing to prolonged delays in this demographic.
The Consequences of Prolonged Gluten Exposure
During the years before diagnosis, ongoing gluten consumption continues to trigger the autoimmune response, causing sustained intestinal damage and nutrient malabsorption. The effects of this delay extend across physical, psychological, and social dimensions.
Physical Impact
- •Persistent intestinal damage and inflammation
- •Nutrient deficiencies affecting bones, nerves, and organs
- •Increased risk of osteoporosis and fractures
- •Elevated risk of other autoimmune conditions
Psychological Impact
- •Prolonged uncertainty and health anxiety
- •Repeated dismissal of symptoms as psychological
- •Frustration from ineffective treatments
- •Impact on mental health and quality of life
Social Impact
- •Disruption to work, education, and daily activities
- •Strain on personal and family relationships
- •Financial burden from repeated medical consultations
- •Social isolation due to unexplained symptoms
A Systemic Challenge, Not Individual Fault
The diagnostic delay in coeliac disease reflects a gap between symptom recognition and clinical testing, not a failure on the part of patients or individual clinicians. Coeliac disease is common, affecting approximately 1% of the population. It is serious when untreated, but highly manageable with early and accurate diagnosis.
Improving awareness across healthcare systems, increasing routine testing in at risk populations, and recognising the full spectrum of coeliac disease presentations are essential steps toward reducing this delay and improving outcomes for those affected.
Important Note
You must continue eating gluten-containing foods before testing. Starting a gluten-free diet before diagnosis can lead to false-negative results and delay proper treatment.
Clinical & Diagnostic Resources
Authoritative organisations providing evidence-based information and support for coeliac disease.
Professional medical guidelines and diagnostic standards for coeliac disease from international experts.
InternationalEuropean diagnostic protocols and clinical practice guidelines for coeliac disease testing.
EuropeComprehensive UK guidance on coeliac disease testing procedures and what to expect during diagnosis.
United KingdomLeading US organisation for celiac disease research, acceleration of diagnosis, and patient support resources.
United StatesNote: External links are provided for informational purposes. We are not responsible for the content of external websites. Always consult healthcare professionals for medical advice.