As everyone is quite aware of, different types of tests usually are performed for the diagnosis of celiac disease. Of course, the first line of choice in this regard is, a thorough physical examination of the patient. The health provider usually performs certain tests to examine for the presence of some of the items in the patient , which include:
1. The presence of emaciation, caused by undernourishment.
2. Pallor, as a result of anaemia.
3. Hypotension, or low blood pressure.
4. Edema, as a result of hypoalbuminemia, which means low levels of albumin in the blood.
5. Skin lesions, such as dermatitis herpetiformis.
6. Easy bruising, caused by vitamin K deficiency.
7. Changes in bone, skin, or mucous membranes caused by vitamin deficiencies.
8. Distended or protruding abdomen, caused by dysmotility of the intestine.
9. Loss of different sensations in extremities such as vibration, light touch and position, caused by vitamin deficiency.
10. Signs of severe deficiencies of vitamins and minerals such as, decreased deep tendon reflexes, spasms of muscle mainly due to deficiency of magnesium and/or calcium; tenderness and pain in the bone due to vitamin D deficiency.
11. Signs of peripheral neuropathy.
Blood or Serological Tests: The gluten-free diet requires avoiding wheat, barley, and rye – products which are in fact staple food items. There is no fixed standardization in the current available tests for the diagnosis of celiac disease. In fact each company utilizes a combination of tests of their own choice, and the numeric value of a normal or abnormal range also differs without any standardization.
Some of the important serologic tests are:
1. Immunoglobulin A anti-endomysium antibodies, abbreviated as EMA.
2. IGA anti-gliadin antibodies, abbreviated as AGA. Studies have reported that, IgA antibodies are not produced by Some people.
3. Deamidated gliadin peptide antibody, abbreviated as DGP.
4. IgA anti-tissue transglutaminase, abbreviated as TTGA.
In fact, these are blood tests for the presence of gluten auto antibodies, which are tests based on IGA, and provide accurate and timely diagnosis of celiac disease, only while on a diet containing gluten. In the year of 2007, the Deamidated gliadin peptide, DGP antibody tests was developed, along with the combination of Tissue transglutaminase, abbreviated as TTG antibodies; and are found to have a better accuracy when compared with native gliadin antibodies. Hence, an abnormal elevation in the levels of endomysial and anti-tissue transglutaminase antibodies are diagnostic criteria that, a person certainly has celiac disease.
Other significant tests may include, Multiplex immunoassay, abbreviated as MIA.
This test helps to provide a simultaneous measurement of multiple antibodies, providing with diminished turnaround time and expenditure. A combination testing helps in the identification of patients, who are individuals for an intestinal biopsy. Test panels also involve AGA in the determination of the capability of a person’s body to make enough IgA antibodies for the EMA and TTG results to be trustworthy. However, deficiency of IgA is in itself not harmful.
Gene tests for the diagnosis of celiac disease: Being a genetic disease, it runs in families. Gene tests alone are not useful in the diagnosis of this disease. Gene tests can only rule out the possibility for the development of celiac disease. Studies have reported that, about 30-40% of individuals in the USA are genetically predisposed to developing this disease.
Human leukocyte antigen, abbreviated as HLA, and region DQ genes are highly characteristic features in individuals diagnosed with this disease. Appropriate genetic tests for this disease necessitate the analysis of the arrangement of both DQA as well as DQB genes. The identification of other genes apart from the HLA area, have and are being performed. Hence, genetic testing may be found of use in family members of an individual diagnosed with celiac disease, as well as in young children as their immune system does not mature. According to the presentation of the researchers of the first population study, the use of a combination of HLA-DQ genes and serological tests in the determination of the prevalence of celiac disease were strongly supported. This non-invasive, combination test may eventually rule out the standard guidelines of a biopsy. The study also recommended the cost effectiveness and efficiency of this process, thus reducing the cost for diagnosis by almost 50%.
Intestinal biopsy: The instructions about the length of time, as well as the amount of gluten containing foods to be consumed prior to the intestinal biopsy should be strictly followed. In fact, the implementation of gluten-free diet should be done only after the completion of the biopsy, and discussion with the gastro-enterologist.
A gastro-enterologist performs a biopsy of the small bowel, usually the jejunum. A small flexible biopsy device is passed through an endoscopic tube in this test, down the gullet, through the tummy(stomach) and then into the upper end of the small bowel where patchy, various scraps of tissue are collected. The endoscopic tube is then removed, and the tissue scrapings are examined for signs of destruction and evidence of celiac disease, under a microscope.
There is a remarkable variation between tissue in a normal small bowel, and that present in a patient with undiagnosed or celiac disease. The normal finger-like projections, known as villi, which increase the surface area of absorption in the small bowel, are partly or completely flattened in a patient with this disease. The enzymes found on the brush border, are also remarkably diminished. The enzymes which are produced at the tips of these villi catabolise carbohydrates. Lactase, the enzyme which is responsible for catabolising lactose, which is the sugar present in milk; and thus it can be absorbed. This is in fact, an example of one of these brush border enzymes. This reduction in lactose gives a clear explanation about the reason for the development of intolerance to milk products by some untreated patients with celiac disease. They may later develop transient or permanent intolerance to lactose. An increased number of T-cell lymphocytes, a type of white blood cells, are also present at the base of the villi.