Celiac Disease*: Diagnosis
1. ProTime blood test
ProTime is a type of blood test that measures the time taken to form blood clots. Vitamin K deficiency, which develops in celiac disease patients owing to reduced absorption of vitamin K, delays blood clotting, producing an abnormal ProTime result.
2. Protein level in blood
Measuring the protein level in the blood helps to assess the severity of malnutrition induced by celiac disease. Low levels of pre-albumen, albumen and transferrin in the blood may indicate celiac disease.
3. Iron and vitamin levels
Malabsorption of nutrients reduces the vitamin and mineral contents in the serum. A blood test helps to determine the level of vitamins B9, B12, D and K, calcium and iron. Poor iron absorption in the small intestine can lead to iron deficiency anemia, which is detected through a blood test.
4. Stool test
Fat malabsorption in celiac disease patients elevates the fat content in the feces, a condition known as steatorrhea, which can be identified through a stool test. After taking the stool specimen, it is stained with a special dye to improve the visibility of the fat globules under the microscope. To improve the accuracy of the test, stool samples are collected for three consecutive days.
5. Capsule endoscopy
In capsule endoscopy, the patient swallows a large capsule containing a tiny wireless camera. Before undergoing capsule endoscopy, the patient is given a laxative to clear the intestines. After the camera enters the small intestine, it takes pictures of the small intestine. The radio receiver present in the capsule transmits the images to a small receiver that the patient undergoing capsule endoscopy wears on the wrist. Nearly 24 hours after swallowing the capsule, the images are transferred from the receiver to a computer for analysis. The capsule is then flushed out of the body through bowel movement. Capsule endoscopy provides a clear picture of the small intestine. Through this process, the doctor can check the condition of the villi.
6. Small intestinal biopsy
Small intestinal biopsy is the most accurate method of diagnosing celiac disease. The sample tissue for biopsy is obtained from the small intestine through esophagogastroduodenoscopy (EGD). During the process, an endoscope is passed into the duodenum through the mouth. A biopsy instrument, present in the endoscope, collects tissues from the lining of the duodenum. Instead of relying on the result of a single sample, multiple samples are collected to increase the accuracy of the biopsy result. A pathologist then examines the sample under a microscope. Loss of villi and presence of excess lymphocytes in the small intestinal tissue indicate celiac disease. However, in cases of cow milk or soy protein allergy and viral gastroenteritis, the result of the small intestinal biopsy may be mistaken for celiac disease.
7. Anti-endomysial antibody test
An anti-endomysial antibody test is one of the most reliable diagnostic tests for celiac disease. In some cases, especially in young children with celiac disease, the test may produce a false negative result. If celiac disease is suspected despite a false negative result, your physician may recommend a small intestinal biopsy.
8. Anti-tissue transglutaminase antibody test
People with celiac disease usually have very high levels of anti-tissue transglutaminase antibody in their blood. These antibodies are produced to fight the tissues of the small intestine. It is a more reliable diagnostic test for celiac disease than the anti-glandin antibody test. However, even people with juvenile diabetes, certain arthritis and inflammatory diseases may have elevated levels of this antibody. Therefore, anti-tissue transglutaminase antibody test is not sufficient for diagnosing celiac disease.
9. Anti-gliadin antibody test
Abnormal immune response to non-infectious substances can stimulate the immune system to release antibodies. In celiac disease patients, sensitivity to a type of glycoprotein called gliadin, found in wheat and several other grains, triggers production of anti-gliadin antibodies. However, anti-gliadin antibody tests are not always reliable. Even people without celiac disease can have abnormally high levels of anti-gliadin antibody in the blood. Nonetheless, this antibody test is recommended especially for monitoring the response of the celiac disease patient to treatment with a gluten free diet.