Saliva Test for Celiac Disease
I’m frequently asked about how Celiac disease (CD) is diagnosed, and people are usually shocked when I list a Saliva Test for Celiac Disease as one option.
As awareness of CD and associated symptoms increases, more people wonder if they, too, have this autoimmune disease.
While that determination warrants several visits to a qualified medical professional (preferably one specializing in CD and gluten-related health issues), I thought it may be helpful to share a brief overview of tests used to diagnose (or rule out) CD.
I’ll also share a novel test being investigated that has promise as an accurate screening tool for CD. That could mean a less invasive, simpler diagnosis. This is particularly encouraging when it comes to diagnosing children.
Testing for Celiac Disease
Note: For accurate results, testing for Celiac disease must be performed when the individual is still eating gluten and has not yet begun a gluten free diet.
First, let me remind everyone, the current definitive test for diagnosing CD is the small intestine biopsy.
This is a test where doctors take a tissue sample from the small intestine lining. It is not typically the first test administered to a potential Celiac, but it is the only test that decisively reveals damage to the small intestine lining and villi. It is noteworthy to point out most specialists in CD testing; treatment and research suggest a single tissue sample is not enough for a determination. Multiple samples – up to 11 in some cases – are recommended from various areas of the small intestine for accurate diagnosis.
Before biopsy is performed, most physicians order several blood tests (also referred to as serological screenings). This is because blood tests are more practical, more affordable, and less invasive than a biopsy.
To understand how these blood tests work, let’s remember what happens inside the body of an individual with CD when gluten is consumed.
Inside the body of an individual with CD, gluten is a threat to the body’s natural defense system (the immune system). When gluten enters, the immune system begins working hard to protect the body.
Think of this as you would the way your body works to fight off a cold or the flu. In that case, unwanted bacteria or a virus enters and the body’s natural defense mechanism kicks in to fight the threat to the system so that you’re feeling better soon.
When the immune system attacks an invader, whether it is gluten or bacteria, antibodies are produced. That’s why an individual with CD who is not yet on a gluten free diet will have higher levels of certain antibodies in their blood.
Blood tests for CD assess levels of these gluten-specific antibodies.
Depending on your physician, some antibodies tested are: tTG (anti-tissue transglutaminase), EMA (anti-endomysium), DGP (anti-deamidated gliadin peptides), IgA (Immunoglobulin gamma A), IgG (Immunoglobulin gamma G).
These blood tests have generally been considered accurate for detecting CD, although false positives and false negatives can (and do) occur.
Now, let’s take a look at another test that some say may be just as accurate… No needles involved!
What Research Says about the Saliva Test for Celiac Disease
It’s controversial, but recent research reported in the Journal of Pediatric Gastroenterology and Nutrition indicates potential CD patients may be able to forego the needle altogether.
In this study conducted in Italy, scientists tested over 5,000 saliva samples from school-age children for antibodies specific to gluten (the same antibodies the blood tests for CD evaluate).
To determine saliva test accuracy, children who tested positive for CD in the saliva test also had blood tests for CD.
Comparing blood test results to saliva test results revealed accuracy of 97%.
Further testing with small intestine biopsy showed a 90% accuracy rate for the saliva test. In other words, for every 10 children who tested positive for CD with saliva screening, 9 were confirmed to have CD via small intestine biopsy.
While the saliva test isn’t 100% accurate, it is proving to be a useful, inexpensive and non-invasive screening tool.
Screening services for the saliva test for food allergies are available in the U.S. from Cyrex Lab and BioHealth Diagnostic. Most alternative medicine providers are familiar with the saliva screening tests available for CD and other food allergies and sensitivities.