(Rev. 9.2013) In brief, the newest blood tests to diagnose Celiac Disease, according to the Beth Israel Deaconess Medical Center are:
– tTG-IgA – tissue transglutaminase-IgA antibody level
– DGP – Deamidated Gliadin Peptide IgA/IgG antibody level*
(the anti-gliadin antibody tests are no longer recommended by BIDMC)
Following is the complete list of recommendations (published on-line 23 April 2013 by the American College of Gastroenterology):
You do not need to see a specialist for the blood tests, your PCP can arrange it.
(Note: 10% of people may have a “negative” blood test and still have Celiac. One reason for this could be an IgA deficiency, which could render a negative result, even though you still have Celiac). If symptoms persist, consider being tested again, especially if a family member has Celiac, and be sure to rule out having a selective IgA Deficiency. *Note: The DGP test can detect an IgA deficiency.
Though blood tests are highly accurate, both “false” negatives and positives can occur. Other reasons for a negative blood test may include:
– May not have active Celiac when tested (keep in mind, CD can be triggered at any age in life, so future testing may be necessary if symptoms occur, especially if there is a family history).
– IgA deficiency (see above)
– Started a gluten-free diet before blood test was given
If you received a “negative” blood test you could consider a genetic test to check for the associated Celiac genes (if you do not have them, you couldn’t possibly have CD); or if you have a family history of CD and still have symptoms, your primary care physician may suggest a biopsy if CD is being strongly considered as a diagnosis. If all are negative, and still experiencing symptoms, Non-Celiac Gluten Sensitivity may be considered as a diagnosis.
What if I am already gluten-free, but want to know if I have Celiac Disease?
From Dr. Dan Leffler of Beth Israel Deaconess Medical Center in Q&A with Huffington Post: “For people already on a gluten-free diet, options are somewhat limited at this time. Our typical recommendation would be to have tTG and genetic testing done first. If the genetic testing is negative, you can be confident that this is not celiac disease. If genetic testing is positive and tTG is positive, this is likely active celiac disease and you can proceed to endoscopy with small intestinal biopsy. However, if genetic testing is positive and tTG is negative, the only way to sort out if someone has celiac disease is through a gluten challenge, which should be conducted under the guidance of a physician experienced in celiac disease.” Read more on “Gluten Challenge” HERE. Note, shorter duration of gluten ingestion may be considered in a Gluten Challenge, discuss with your gastroenterologist.
If blood tests are positive (elevated levels) this suggests Celiac is present. Next, to aid in the diagnosis, a small intestinal bowel biopsy* will, in most cases, be performed, where an endoscope is passed through the mouth into the small intestine to look for abnormalities such as inflammation and damage to the villi [Note: It is recommended to have 4-6 biopsy samples taken during the endoscopy, not just 2]. Also consider a capsule endoscopy where a tiny camera is swallowed and allows doctors to see inside the small intestine, an area that isn’t easily reached with conventional endoscopy, according to the Mayo Clinic. Once on a gluten-free diet, the absence of symptoms combined with the intestinal biopsy, would confirm a diagnosis of Celiac. A repeat biopsy may occur once the individual has been on a gluten-free diet for a period of time, to check for intestinal healing. A biopsy may be recommended even if the blood test is negative, under certain conditions.
*the small intestinal biopsy had always been considered the “gold standard” in a final diagnosis of Celiac, until recently. According to Dr. Alessio Fasano, MD, director of the Center for Celiac Research at the University of Maryland School of Medicine, it is being considered whether the biopsy would be necessary for a diagnosis if the person fulfilled the majority of certain criteria (i.e. symptoms, antibodies, genes, improvement from GF diet). To date, the small intestinal biopsy is still considered the “gold standard”, but this may change in the future. Here is a recent study relating to this: http://www.biomedcentral.com/1471-230X/13/19
Important to note: A self-diagnosis of Celiac, and start of a gluten-free diet, is strongly discouraged by medical professionals. Gluten must be present in the body at the time of the blood test and biopsy, otherwise the test results could be unreliable. ” (From the University of Chicago, Celiac Disease Center regarding Biopsy: “Any changes in your diet can affect the accuracy of your biopsy results. It is necessary for you to be eating gluten every day for at least 12 weeks before the procedure. If you are scheduled for a biopsy and are not eating gluten, talk to your doctor about what is necessary to obtain accurate results. If you have a biopsy and have eaten gluten only a short time before the test, you and your physician will not know if a negative test result is accurate or due to your diet.”
Do not delay your diagnosis. If you suspect you have Celiac, make an appointment with your primary care physician or gastroenterologist. (See Resources for a list of gastroenterologists in your area).
At-Home Celiac Test
There is a Celiac Test available which you can use in the convenience of your home. It is called the BIOCARD Celiac Test, distributed by 2G Pharma Inc., Ontario. Keep in mind it should only be used as an aid in providing an immediate diagnosis (within 10 minutes), and you should confirm a diagnosis with a medical doctor, BEFORE commencing a gluten-free diet. See our Store/Test Kits.
The British Society of Gastroenterology’s Diagnosis and Management of Adult Coeliac Disease Guidelines (Revised April 2014)as featured in Gut.bmj.com, open HERE.
Article from University of Chicago Celiac Disease Center (Jan. 2012 Newsletter) “Evolving Diagnostic Criteria for Celiac Disease” http://www.cureceliacdisease.org/wp-content/uploads/2012/01/CdC_Newsletter_0112_v4-link.pdf ; Celiac Disease: New Guidelines for Diagnosis and Management (2013).