About Celiac Disease Blood Tests
The medical community has devised a prescribed method for diagnosing celiac disease, an autoimmune disorder.
Sufferers of this condition are susceptible to elevated antibodies in their bloodstream, particularly after the consumption of gluten based products. Various preliminary and diagnostic tests may be used to detect celiac disease.
Autoimmune diseases, such as this, often proliferate into more perilous, secondary conditions.
By definition, an autoimmune disease perceives a natural substance as a pathogen or foreign invader, thereby waging an attack against the body itself.
In the context of celiac disease, the body identifies gluten as the invasive pathogen and launches an immune attack against bodily tissue.
Subsequently, the body’s antibodies attempt to extinguish the presence of tTG, or tissue transglutaminase in the intestines.
Specifically, two distinct antibodies are responsible for decimating tTg, and they include IgA and IgG. IgA is synthesized in the small intestine, and it is easily detectable in the blood stream-hence the advantage of conducting an IgA blood test.
IgG levels, however, do not necessarily indicate the presence of celiac disease because it plays a prominent role in other diseases, as well. Generally speaking, there are many signs that suggest the presence of an autoimmune disease.
General Test Information
Conducting the blood test with accuracy is critical in terms of diagnosing this condition.
To ensure accurate results, it is important that the subject have a diet entailing the consumption of gluten based foods, including pasta and bread.
This is because gluten consumption permits the synthesis of antibodies correlated with this disorder.
While these tests are relatively safe, blood drawing can sometimes lead to fainting, lightheadedness, pain at the injection site and a hematoma.
Test tTG-IgA Test
One of the most commonly administered exams is that of the tTG-IgA test, which translates roughly to Tissue Transglutaminase Antibodies.
This diagnostic assessment produces either a negative or positive test result, which indicates the lack or presence of these antibodies, respectively.
Although the test has been solidified and refined for accuracy, there are potential margins for error.
In 98% of celiac disease sufferers, the test will precisely indicate a positive test result. 95% of celiac-free individuals who get tested come back negative.
Hence, the test’s specificity is relatively high, but not entirely impenetrable to error. It is frequently observed that individuals with other autoimmune disorders induce a false positive result.
These diseases include chronic liver disease, and Type 1 Diabetes. Additional tests, of course, may be administered to decrease the likelihood of a false negative or false positive.
To execute this test, the health professional simply sterilizes the skin with an antiseptic, and draws blood from a vein.
Prior to this, however, a tourniquet is applied in the upper arm region to increase the prominence of the vines before blood is drawn.
The needle is then inserted into the arm, and blood is then drawn into a vial. Once the tourniquet and the needle are removed, the blood sample is assessed for the presence of the antibody. During the test, the subject will only experience a state of mild discomfort.
Once the blood sample is obtained, a machine processes it for the presence of the indicated antibody, and the test results are confirmed in 24-48 hours.
Generally speaking, if the test indicates that celiac disease-related antibodies are present, the doctor will follow up with subsequent tests.
One such test would include a small intestine biopsy, which would screen for signs of inflammation.
IgA Endomysial Antibody (EMA) Test
This test is reserved for celiac disease patients who have elusive test results, or those who are simply difficult to diagnose.
EMA, which refers to the antiendomysial antibodies, are synthesized to attack bodily tissues. IgA is the antibody that is responsible for this.
While IgA generally helps detect foreign pathogens, including bacteria and toxins, celiac disease operates quite differently.
This test is characterized by a specificity level of almost 100%. However, it lacks a viable level of sensitivity, in terms of detecting the intended antibodies. 5%-10% of individuals who are given the EMA test do not produce a positive test result.
Furthermore, the aforementioned test is far more cost-effective than the EMA test. The EMA test is slightly more invasive, as it involves the primate esophagus or an umbilical cord.
Because this celiac disease blood test conveys the most accuracy, patients that test positive virtually always have the disease.
Total Serum IgA Test
This test is structured to identify an IgA deficiency, an issue closely correlated with the presence of celiac disease.
This deficiency can occasionally result in a false positive result. For this reason, when a test subject tests positive, the doctor conducts a series of additional tests to confirm a positive diagnosis. Generally speaking, an endoscopy is required for an official diagnosis.
Deamidated Gliadin Peptide (DGP IgA and IgG)
These tests are implemented for additional screening measures, and they can accompany the previously mentioned tests.
These deamidated proteins are highly beneficial because they increase the sensitivity of the test’s antibody detection, and they aid singlehandedly with the diagnostic process.
These peptides are detected with the aid of an enzyme-linked immunosorbent assay, which attaches itself to the deamidated peptides. This facilitates detection of the antibodies involved in celiac disease.
Those who suffer from celiac disease are considered carriers of the HLA DQ2 and DQ8 genes. A celiac disease sufferer may carry one or both of these genes.
Of course, 40% of all people carry one or both of these genetic alleles. Of course, an individual who lacks both of these genes will surely never develop the disease.
If a test indicates that the genes are present, antibody testing would be the next viable step in this process. The genetic test is relatively basic, and merely requires a cheek swab, saliva test or blood test.
Regarding Invasive Test Methods
As noted, biopsies are conducted to obtain intestinal samples of the subject, but they prove to be invasive and uncomfortable in many cases.
For this reason, serologic tests may be used diagnostically to confirm or disconfirm the presence of celiac disease.
Selecting the Right Physician
Selecting the right medical professional is absolutely key, in terms of easing your transition to a newly diagnosed state and gluten free lifestyle.
The CDF Healthcare Practitioner Directory comprises a list of professionals who specialize in this disease.