Celiac disease test – What tests are used to diagnose celiac disease?
Celiac disease tests help to clarify whether someone has a gluten intolerance. Due to incorrect diagnostics, it often takes years to diagnose celiac disease. Sometimes celiac disease remains undiagnosed for a lifetime. Celiac disease can be identified in good time based on certain blood values, colonoscopies, biopsies, stool and genetic tests. In this article you will learn which steps are necessary for this.
Who is affected by celiac disease?
Various celiac tests are used to diagnose celiac disease (indigenous sprue) and, if necessary, in combination. Celiac disease is an autoimmune disease that affects approximately 3 out of 1,000 people in Germany. After contact with the grain protein gluten the body forms antibodies against the body's own structures. Among other things, the antibodies attack the intestinal mucosa. Those affected report indigestion. There may also be other symptoms.
The therapy for celiac disease is a gluten free diet. Medications are usually not necessary. It’s best if a nutritionist who specializes in celiac disease supports the change in diet. We have developed a special nutritional therapy for food intolerances. Together with your nutritionist, you will find out here what you can tolerate well and how to establish eating habits that are really good for you. Arrange a free informational meeting here and find out more.
For those affected, however, a correct diagnosis is always important to prevent symptoms or complications from starting a gluten-free diet. In this article, we present the guidelines-based celiac disease tests.
Who should be tested for celiac disease?
Celiac disease causes undetected and untreated symptoms. In addition, with untreated celiac disease, the risk of cancer of the lymphoid tissue in the intestine is significantly higher than in the normal population or in those affected who follow a gluten-free diet. It is therefore important that the disease is diagnosed in as many people as possible. This is a challenge, as not all sufferers report typical celiac symptoms.
The guidelines of the American College of Gastroenterology (ACG) also cover the topic of celiac disease diagnosis. The ACG recommends testing for celiac disease for the following patient groups:
- Symptoms: Patients with symptoms or laboratory values that indicate a disturbance in the absorption of nutrients in the intestine (malabsorption). Symptoms include long-term diarrhea, fatty stool, weight loss and/or severe gas and stomach pain after meals. Laboratory values that can be an indicator of indigestion are vitamin B12, iron, vitamin K and folic acid. A lack of these substances can indicate malabsorption.
- Laboratory values: Patients with symptoms or laboratory abnormalities that can in principle be caused by celiac disease. The difference from the first group is that the symptoms are not directly related to malabsorption. Possible symptoms include indigestion of any kind and, for example, laboratory calcium deficiency, which can ultimately lead to bone loss (osteoporosis).
- Liver function tests: Patients with elevated liver function tests (transaminases) in the blood count, unless there is no other explanation.
- Relationship: Patients whose first-class relatives have securely diagnosed celiac disease and who have symptoms or abnormal laboratory results that may be related to celiac disease.
- **Relatives, but no symptoms: **A celiac test may also be indicated in patients without symptoms with first-class relatives who have been diagnosed with celiac disease. After a positive test and adherence to a gluten-free diet, it often turns out that the person concerned had symptoms before. These symptoms may not have been of any significance beforehand or the person concerned did not consider them worth mentioning.
- Type I diabetes: Patients with type I diabetes mellitus (adolescent form of diabetes) and symptoms or laboratory abnormalities that can in principle be associated with celiac disease. The background to this is that in type I diabetes mellitus antibodies are also formed in many cases, which are directed against the body's own structures. It is then more likely than normal that antibodies will also be formed, such as those found in celiac disease.
In summary, these guidelines are intended to ensure that there is increased vigilance regarding celiac symptoms. As a result, patients with celiac disease can actually be recognized.
What tests are used to diagnose celiac disease?
Various tests can be used to diagnose celiac disease. The test materials are blood and tissue samples from the small intestine. The tests described lead to usable results only with a diet containing gluten. Later they help to monitor the course of celiac disease on a gluten-free diet:
- Detection of antibodies typical of celiac disease in the patient's blood
- Blood test for selective IgA deficiency
- Antibody test in children
- Taking a tissue sample (biopsy) from the small intestine
- Blood test with a negative antibody test and suspicious tissue sample
Detection of antibodies typical of celiac disease in the patient's blood
Detection of tissue transglutaminase antibodies or endomysium antibodies of the subgroup IgA can be carried out in the blood. The antibodies attack the body's own tissue. The accuracy of these antibody tests varies from laboratory to laboratory and also from test set to test set. Good tests correctly identify people with celiac disease with 95% probability (sensitivity). A positive test result also means that the affected person is actually ill with 95% probability (specificity). Various test methods exist. In a frequently used test variant ELISA, the blood sample is diluted and applied to a plate. Binding sites are provided on the plate to which the antibodies seek to bind. The blood sample is washed off the plate. The antibodies stick to the plate due to the binding sites. The antibodies can be made visible with a second test solution. The concentration of the tTG-AK or Em-Ak is then determined.
Blood test for selective IgA deficiency
Five to ten out of a hundred celiac patients have a so-called IgA antibody deficiency syndrome and do not form antibodies of the IgA subgroup. If IgA antibody deficiency syndrome is suspected, the blood should also be tested for the corresponding IgG class antibodies. The test also works according to the Elisa principle.
Antibody test in children
The immune system in children is not yet fully developed. This increases the likelihood that no celiac disease-typical antibodies can be detected in the blood. For this reason, blood in children under two years of age is tested for both the respective IgA and IgG antibodies. The tests are designed to ensure that children with celiac disease are actually recognized.
Taking a tissue sample from the small intestine
The removal of tissue samples (biopsies) from the small intestine is performed for every justified suspected case of celiac disease, regardless of the results of the antibody tests. Except for children, a reliable diagnosis is very likely possible without taking a sample if tTG-Ak or Em-Ak are detectable. The tissue samples are taken during gastroscopy, in which the examiner pushes the examination instrument right down into the small intestine. The mucosal samples are examined microscopically. Possible abnormalities are atrophic changes and inflammatory reactions of the intestinal mucosa, but not in the underlying tissue layers.
Blood test with a negative antibody test and suspicious tissue sample
In the case of a tissue sample with suspected celiac, but negative antibody tests, the blood can be checked again for the presence of certain genes (HLA-DQ2 or HLA-DQ8). If this test is positive in addition to the tissue sample, celiac disease is very likely.
Which laboratory values are noticeable in celiac disease?
Celiac disease can lead to changes in blood laboratory values. The following laboratory values can be suspect:
- Vitamins and minerals: Lowered levels of vitamin B12, folic acid, vitamin K, iron and iron (ferritin). Lower levels of magnesium, calcium and potassium may also be present
- Malnutrition marker: Decreased protein levels in the blood (albumin)
- Blood clotting: Impaired coagulation with decreased partial thromboplastin time (PTT)
- Blood count: Anemia (decreased hemoglobin and red blood cell count), red blood cell enlargement (macrocytic erythrocytes); the corresponding laboratory values are called Hb, erythrocyte count, MCV and MCH
- Liver function tests: Increase in the transaminases GPT and GOT
- Special antibodies: Tissue transglutaminase antibody (tTG-Ab), endomysium antibody (EmA-Ab), anti-gliadin antibody (AGA-Ab)
- Genetic testing: Possibly detection of the HLA-DQ2 or HLA-DQ8 genes
Is a lab test enough to diagnose celiac disease?
Both the American and German gastroenterological guidelines recommend follow up with a small intestine biopsy after positive laboratory test to secure a diagnosis of celiac disease. The diagnosis then justifies compliance with a lifetime** gluten free diet**. (Click here for gluten-free recipes) It is also important to identify patients who have a different underlying disease despite symptoms that are suspected of being celiac-related and positive blood tests.
In the future, however, there should be tests that no longer require the removal of tissue samples (biopsies) from the small intestine to confirm the diagnosis of celiac disease. In individual cases, the biopsies can already be dispensed with if there is a high probability of celiac disease. Then a gluten-free diet is started. A decrease in symptoms speaks for the diagnosis of celiac disease, however, does not exclude competing diagnoses such as wheat allergy or wheat sensitivity.
Can a blood test after starting a gluten-free diet confirm the diagnosis of celiac disease?
After initiating a gluten-free diet, the disease activity of celiac disease decreases. The small intestine tissue shows little or no abnormalities, and the antibody levels in the blood with suspected celiac disease also decrease. An antibody test or taking a tissue sample can be negative on a gluten-free diet, even though you have celiac disease. The blood test for the gene HLA-DQ2 or HLA-DQ8 can also contribute to the diagnosis:
- The blood test for HLA-DQ2 and HLA-DQ8 is negative: Celiac disease is then excluded. Another type of gluten sensitivity may be present.
- The blood test for HLA-DQ2 and HLA-DQ8 is positive for one of the genes: The presence of celiac disease is then possible. The affected person should then consume gluten for a few weeks in order to then carry out an antibody test again and, if celiac disease is suspected, a biopsy. The presence of the HLA-DQ2 or HLA-DQ8 genes alone is not sufficient to diagnose celiac disease.
For a first assessment of the personal risk of celiac disease, our doctors have developed a self-test for celiac disease. Find out about the test here.
Can celiac disease also be diagnosed in stool?
No, it is not possible to diagnose celiac disease through testing the stool. Typical for malabsorption in celiac disease is malodorous, shiny stool that still contains a lot of fat. Some laboratories offer a fat content measurement in the stool collected over 72 hours. Fatty stool is just a sign of malabsorption. However, it does not indicate why the body is not absorbing fat. Another cause is an underactive pancreas, for example.
Where is celiac disease diagnosed?
A reliable diagnosis of celiac disease is only possible with sound diagnostics and correct interpretation of the test results. The diagnosis of celiac disease is far-reaching for those affected. They must adhere to a gluten-free diet for life, and the disease must be monitored so complications are prevented. The diagnosis should therefore always be done with a** gastroenterological specialist**. The gluten-free diet must also be carried out under guidance to prevent nutrient deficiency. With Cara Care, we offer a special nutritional therapy that is tailored to the needs of people with celiac disease. Find out in a free initial consultation whether the therapy is suitable for you.
How safe are celiac disease tests from the drugstore or pharmacy?
Indigestion is common. And many sufferers shy away from seeing a doctor. The suspected diagnosis of celiac disease quickly appears when looking for causes of the symptoms. The drugstores, internet shops and pharmacies take advantage of this and offer over-the-counter tests for celiac disease. The tests **suggest **that the diagnosis of celiac disease can be made quickly, reliably and easily at home from blood or stool samples. For example, celiac disease tests are sold at:
- Internet pharmacies
- Amazon and other internet mail order companies
The tests cost between 12 and 100 euros. But be careful! **The introduction of over the counter celiac disease tests has received **harsh criticism, among others by the German** Society for Celiac Disease.** The tests are not standardized, nor is the diagnosis made by a doctor. Over-the-counter celiac disease tests provide hardly any useful information as to whether you have celiac disease. Most drugstores, such as dm, Rossmann and Müller, have withdrawn the tests due to strong criticism.
How is it possible to estimate the risk of celiac disease as an individual?
The diagnosis of celiac disease should be made by a doctor. Well-founded self-tests can provide an orientation as to whether celiac disease is possible in principle. Reizdarm.one has developed a questionnaire that can help with diagnostics. You can take the self-test for celiac disease there. However, the test does not replace a medical diagnosis.
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Lebwohl, B., Granath, F., Ekbom, A., Smedby, K. E., Murray, J. A., Neugut, A. I., ... & Ludvigsson, J. F. (2013). Mucosal healing and risk for lymphoproliferative malignancy in celiac disease: a population-based cohort study. Annals of internal medicine, 159(3), 169-175., Online: http://annals.org/aim/article-abstract/1722497/mucosal-healing-risk-lymphoproliferative-malignancy-celiac-disease-population-based-cohort, downloaded on 24.03.2018
Marsh, M. N. (1992). Gluten, major histocompatibility complex, and the small intestine: a molecular and immunobiologic approach to the spectrum of gluten sensitivity (‘celiac sprue’). Gastroenterology, 102(1), 330-354., Online: http://www.gastrojournal.org/article/0016-5085(92) 91819-P/fulltext, downloaded on 24.03.2018