How is celiac disease diagnosed?

Celiac disease is an autoimmune condition wherein your immune system overreacts and attacks its own gut (small intestines) tissues whenever you eat gluten rich food. 

Gluten is a binder protein found in wheat, barley, and rye. These grains are common ingredients when making pasta, pizza, cereal, cakes, bread and even beer! (Harvard T.H. Chan School of Public Health, n.d.)

If a gluten sensitive person starts eating foods with gluten, it thinks gluten is a toxin and this triggers inflammation.  Mild symptoms includes tiredness or fatigue, bloating, farting and alternating between diarrhea and constipation. Celiac disease also damages the surface of the small intestines causing severe symptoms like malabsorption and loss of required nutrients. It is common to notice unintentional weight loss, and malnutrition and issues with motor coordination, balance or speech.

There is no clear explanation on the main cause of this autoimmune disease, but scientists say that it is a combination of genetics and the environment.

So who should get screened for celiac disease? Anyone older than three years old experiencing the symptoms described above, parents, siblings or children of people with celiac disease and any individual associated autoimmune disorder like type 1 diabetes, Williams syndrome, Down syndrome, autoimmune liver disease, selective immunoglobulin A (IgA) deficiency, Turner Syndrome or thyroid diseases. (webmd, n.d.)

To rule in this diagnosis, a physician will check the symptoms the patient is having. This includes a thorough check of your medical and family history. Since this disease is sometimes hereditary, if you have a first-degree relative who is diagnosed with it, this information should be disclosed. Celiac disease is also closely linked to people who have associated autoimmune disorder. Knowing these things will help the doctor decide whether he should screen you further for celiac disease.

During the physical exam, the doctor is going to check for signs of growth retardation or unexplained weight loss. Auscultation of the stomach will be done as well. He will also check for severely itchy inflamed blistering rash. This is commonly found in the elbows, knees, buttocks, back and scalp. This is called dermatitis herpetiformis or “gluten rash” or the “celiac disease rash”. (Healthline, n.d.)

A dental check is also done because people with celiac disease often have eroded tooth enamel and persistent canker sores. 

However, celiac disease cannot be diagnosed by symptoms alone because it resembles other ailments like lactose intolerance or irritable bowel syndromes. Therefore, several procedures are done to triangulate and help diagnose the disease.

Blood tests. Celiac diseases is diagnosed by first collecting your blood sample for celiac serology and genetic testing. To get an accurate celiac diseases blood test, you should be on a gluten rich diet. There is no need to restrict gluten intake until celiac diseases is diagnosed and confirmed. However, if you are already in a gluten-free diet, you will undergo a “gluten challenge” under the supervision of your doctor. Adults, you will eat four slices of wheat-based bread every day for eight weeks prior to the test. Children need only to consume half of this serving size. This is needed so results will not come out as falsely negative.

The Tissue Transglutaminase IgA antibody (tTG-IgA) is the best way to test for celiac disease because 93% of patients with this disease will test positive. However, people with associated autoimmune disorder like type 1 diabetes, Hashimoto’s thyroiditis, autoimmune liver disease, psoriatic or rheumatoid arthritis and heart failure who has no celiac diseases might have a false positive result.

People with celiac disease have an elevated level of IgA antibody proteins. This indicate an immune reaction to gluten in the bloodstream. Other blood tests could also be done to determine if you have iron deficiency anemia and other vitamin and mineral deficiency as a result of malabsorption of nutrients in the body.

HLA genetic testing. If the celiac serology or small bowel biopsy is vague and difficult to interpret, the HLA genetic testing is usually done. A blood sample is usually collected. However, other methods like putting saliva under the microscope or scraping the inner cheek could also be done. HLA-DQ2 and HLA-DQ8 gene variants or parts of these genes are present in over 99% of those who have the diseases. Therefore, if you have this in your genes, there is a high probability that you have celiac diseases. 

Celiac serology and genetic testing alone cannot make diagnosis for celiac disease. This should be followed by a small bowel biopsy for a confirmatory diagnosis.

Upper GI endoscopy. The next procedure is an upper gastrointestinal endoscopy. This is a minor procedure done under light anesthesia. A small camera is inserted through the mouth until the intestinal tract to check the villi in the small intestine for villous atrophy or damage. Several small samples of tissue is then harvested from the small intestine for biopsy and to check for signs of celiac disease. This procedure just takes 15 minutes. If your biopsy tests negative but taking in gluten causes you some celiac diseases-like symptoms, you may have “non-celiac gluten sensitivity”. Because of the potential for false antibody test results, this procedure is the only way to diagnose celiac disease.

 

Skin biopsy. Lastly, if a patient appears to have dermatitis herpetiformis, the doctor will remove a small piece of skin tissue for biopsy to confirm it. This will be done under local anesthesia.  

Other procedures that might be recommended by your GP is a DEXA scan. DEXA scan is an x-ray procedure that measures bone density. In people with coeliac diseases, poor absorption of vitamins and minerals can also lead to osteoporosis. With osteoporosis, the bones becomes weak and brittle and increases your chances of getting fractures as you age.

 

Some doctors may encourage you to take a test for food intolerances, testing for gluten-intolerance genes or IgG antibody testing to rule out celiac disease. Other unnecessary procedures include cytotoxic food testing, Alcat testing, Vega testing, allergy elimination techniques, pulse testing, Rinkel’s intradermal skin testing, kinesiology, reflexology, iridology, and hair analysis. These procedures are not evidence based and may have misleading results that does not necessarily contribute to the final diagnosis of the disease. These things can delay you from seeking proper medical attention. (Coeliac Australia, n.d.)

References:

Overview: Coeliac Disease. (03 December 2019). NHS. Retrieved 23 August 2022 from https://www.nhs.uk/conditions/coeliac-disease/

Diagnosis of Celiac Disease. (October 2020). National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved 23 August 2022 from https://www.niddk.nih.gov/health-information/digestive-diseases/celiac-disease/diagnosis

Gluten: A Benefit or Harm to the Body? (n.d.) Harvard T.H. Chan School of Public Health. Retrieved 23 August 2022 from https://www.hsph.harvard.edu/nutritionsource/gluten/

Diagnosis: Why a medical diagnosis is important. (n.d.) Coeliac Australia. Retrieved 23 August 2022 from https://www.coeliac.org.au/s/coeliac-disease/diagnosis

Celiac Disease Diagnosis. (n.d.) Mayo Clinic. Retrieved 23 August 2022 from https://www.mayoclinic.org/diseases-conditions/celiac-disease/diagnosis-treatment/drc-20352225

Celiac Disease Testing and Diagnosis. (n.d.) Beyond Celiac. Retrieved 23 August 2022 from https://www.beyondceliac.org/celiac-disease/get-tested/

Robinson, Jennifer. (2020, November 19). How Do I Know If I Have Celiac Disease? WebMD. https://www.webmd.com/digestive-disorders/celiac-disease/celiac-disease-diagnosis-tests

Lights, Verneda. ( 2018, September 17). Celiac Disease: More Than Gluten Intolerance. Healthline. https://www.healthline.com/health/celiac-disease-sprue