Arriving at a diagnosis
If you think you have celiac disease the first thing NOT to do is change your diet; there are various types of tests for celiac disease including blood tests for measuring antibodies, intestinal biopsy and genetic testing. A definitive diagnosis, however, can be made only on the basis of an intestinal biopsy while the person is on a gluten containing diet. In this procedure, a tissue sample from the small intestine is collected and then viewed under a microscope, which can reveal possible damage to the intestinal villi.
Certain blood tests are useful in screening for celiac disease. Primarily among these is the highly reliable tests for antibodies. Tissue translutaminase antibodies (tTg-IgA) is very sensitive and the anti-endomysial antibodies (tTg-IgA) is very specific. Tests for antigliadin antibodies (AGA) are particularly helpful in screening children under the age of three. These tests for celiac disease are dependent on the body’s ability to make serum IgA, therefore an additional test for serum IgA should be done, including total serum IgA and deamidated gliadin peptide (DGP IgA & IgG). Speak to your doctor about this.
In the event that the blood tests are positive, the next step is to perform an intestinal biopsy, a procedure in which tissue samples from the small intestine are taken by means of an endoscope and then analyzed under a microscope. If the characteristic alterations in the intestinal lining (blunting of the villa and an increase in intraepithelial lymphocytes) are found, a definitive diagnosis of celiac disease can be made.
Family members of those with celiac disease are approximately ten times more likely than the general populations to develop the disease therefore in some cases, genetic testing may be helpful in ruling out celiac disease but not for diagnosing the disease. The HLA-DQ2 and/or DQ8 genes are present in the vast majority (at least 95%) of people with celiac disease. The presence of HLA-DQ2/DQ8 alone, however, does not necessarily lead to a development of the disease, as these same genes are found in a high percentage of healthy individuals (20 to 30% of the general population).
If your test is negative but you are still experiencing the symptoms of celiac disease, speak to your doctor about gluten sensitivity. Gluten sensitivity is a more common problem than you might think. According to authoritative studies, an increasing number of people are suffering from disorders that could be related to gluten sensitivity and following a gluten-free diet can be beneficial for them too.