Celiac disease is an autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. Gluten is a protein found in wheat, rye, and barley. For those with celiac disease, consuming gluten triggers an immune response in the small intestine, which over time damages the small intestine’s lining and prevents nutrient absorption. Many people live with celiac disease without knowing it, attributing their symptoms to other causes. Accurate diagnosis is the first step to managing this condition and improving quality of life.
Two initial blood tests are crucial in the diagnostic process for celiac disease: serology testing and genetic testing.
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Serology Testing: This blood test is the first step in identifying a potential immune reaction to gluten. It looks for elevated levels of specific antibodies in your blood, such as tissue transglutaminase IgA (tTG-IgA) and anti-endomysium antibodies (EMA). These elevated antibody levels suggest that your immune system is reacting to gluten, which is a key indicator of celiac disease.
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Genetic Testing (HLA-DQ2 and HLA-DQ8): This test analyzes your genes for the presence of human leukocyte antigens HLA-DQ2 and HLA-DQ8. While these genes are found in a significant portion of the general population, they are present in nearly everyone with celiac disease. A negative genetic test can effectively rule out celiac disease, as these genes are necessary (but not sufficient on their own) for developing the condition. However, a positive genetic test only indicates a predisposition and doesn’t confirm celiac disease.
It is vital to undergo testing for celiac disease before starting a gluten-free diet. Eliminating gluten prior to testing can lead to false negative results on serology tests, making diagnosis more challenging and potentially delaying necessary treatment and management.
If blood tests suggest celiac disease, further confirmatory testing is usually required. The most common and definitive tests are endoscopy and, in some cases, capsule endoscopy.
Endoscopy
Endoscopy is a procedure that allows your doctor to directly visualize the lining of your upper digestive tract, including the esophagus, stomach, and duodenum (the first part of the small intestine). During an upper gastrointestinal endoscopy, a thin, flexible tube equipped with a light and a tiny camera (endoscope) is gently inserted through your mouth and down into your esophagus.
The camera transmits real-time images to a monitor, enabling the doctor to examine the lining of these organs for any abnormalities. Specifically for celiac disease diagnosis, the doctor will look for damage to the villi in the small intestine. Villi are small, finger-like projections that line the small intestine and are responsible for nutrient absorption. In celiac disease, these villi are flattened or damaged due to the immune response to gluten.
During the endoscopy, the doctor will also take small tissue samples, called biopsies, from the duodenum. These biopsies are then sent to a laboratory for microscopic examination. A pathologist will analyze the tissue samples to confirm the presence of villous atrophy (damage to the villi) and other characteristic changes indicative of celiac disease. Endoscopy with biopsy is considered the gold standard for confirming celiac disease diagnosis in adults.
Capsule Endoscopy
Capsule endoscopy is a less invasive procedure that provides images of the entire small intestine, which is longer and harder to reach with a traditional endoscope. For capsule endoscopy, you swallow a small, disposable capsule, about the size of a large vitamin pill, that contains a camera, lights, and a transmitter.
As the capsule naturally travels through your digestive system, propelled by normal intestinal contractions, the camera takes thousands of images of the lining of your small intestine. These images are wirelessly transmitted to a recorder that you wear on a belt around your waist. The procedure is painless and doesn’t usually require sedation.
Capsule endoscopy is particularly useful in situations where the diagnosis is uncertain after upper endoscopy, or when there is suspicion of damage further down in the small intestine that is not reachable by standard upper endoscopy. It can be helpful in identifying celiac disease complications or in cases where a complete examination of the small intestine is needed.
After approximately 8 hours, or when you have a bowel movement, the capsule is naturally expelled from your body and flushed away. You will return the recorder to the clinic, and the images will be downloaded and reviewed by a gastroenterologist to assess for any signs of celiac disease or other abnormalities.
Dermatitis Herpetiformis Diagnosis
Dermatitis herpetiformis (DH) is a skin manifestation of celiac disease, characterized by an intensely itchy, blistering rash. For individuals presenting with symptoms of DH, a skin biopsy is a crucial diagnostic step. A small sample of skin tissue is taken from near a blister and examined under a microscope.
The skin biopsy for DH looks for specific IgA antibody deposits in the skin. The presence of these deposits, along with the characteristic rash, is highly indicative of dermatitis herpetiformis and, by extension, celiac disease. Individuals diagnosed with DH are considered to have celiac disease, even if they don’t have typical gastrointestinal symptoms.
Additional Testing and Nutritional Assessment
Once celiac disease is diagnosed, further testing may be recommended to assess for potential complications and nutritional deficiencies. Celiac disease can affect nutrient absorption, leading to deficiencies in essential vitamins and minerals. Common additional tests include:
- Nutritional Status Assessment: Blood tests to check levels of vitamins A, B12, D, E, folate, iron, copper, zinc, and calcium.
- Complete Blood Count (CBC): To check for anemia.
- Liver Enzyme Tests: To assess liver function, as celiac disease can sometimes affect the liver.
- Bone Density Scan (DEXA scan): To evaluate bone health, as malabsorption of calcium and vitamin D can lead to decreased bone density and osteoporosis.
These additional tests help to understand the impact of celiac disease on your overall health and guide treatment and management strategies, including dietary modifications and potential supplementation.
Importance of Expert Care
Navigating the diagnostic process for celiac disease can be complex. Consulting with healthcare professionals experienced in celiac disease is essential for accurate diagnosis and personalized management. A gastroenterologist can guide you through the appropriate testing, interpret results, and develop a comprehensive care plan. A registered dietitian specializing in celiac disease can provide crucial support in implementing and maintaining a gluten-free diet, which is the cornerstone of celiac disease management.
Early and accurate diagnosis of celiac disease is crucial to prevent long-term health complications and improve the quality of life for those affected. If you suspect you may have celiac disease, it is important to seek medical advice and undergo appropriate testing to receive a definitive diagnosis and begin effective management.
