by Dr. Vikki Petersen
At HealthNOW Medical Clinic San Jose we know that, as if it wasn’t hard enough to convince some doctors to do a celiac disease test—let alone one for gluten sensitivity—once you finally DO get tested, the interpretation of the results can be faulty.
While you shouldn’t have to question your doctor, unfortunately when it comes to the interpretation of lab tests relating to celiac disease or gluten sensitivity, you may have to learn some test interpretation lingo in order to save your own health.
Don’t worry about it being difficult to learn this data. I’ll make it easy to understand. The important thing to know is that if you don’t feel well, there is a reason. It may be a problem with gluten, it may be something else, but it IS something. Don’t give up. If you need my help, I’m here for you!
Celiac Disease Test: What You Need to Know
Before jumping into the lab test, I wanted to clear up a couple of words you commonly hear regarding tests—and that is their sensitivity and specificity. The definitions of these words are as follows:
Sensitivity simply means the true positive rate or the proportion of positive results are correctly identified. If 90% of celiacs were correctly identified by a certain test, it would be said to have a high sensitivity.
Specificity is the opposite and is often called the true negative rate. It is the proportion of negative results which are correctly identified. If a test identified correctly 90% or more of healthy people as having a negative result, that test would be considered to be highly specific.
A perfect test (it doesn’t yet exist) would be one that was 100% sensitive and 100% specific.
The tests we are about to discuss detect autoantibodies which are substances the body auto creates as part of an immune response to dietary proteins it considers are toxic (antibodies)—such as gluten and gliadin. These autoantibodies can cause intestinal inflammation and damage in the lining of the intestinal wall as well as other parts of the body, resulting in autoimmune disease.
Below are some commonly used lab tests for celiac disease and gluten sensitivity. Feel free to use this section as a reference for the later section which discusses real life examples that people have shared after receiving a celiac disease test:
tTG Celiac Disease Test
Anti-tissue Transglutaminase Antibodies, IgA – abbreviated tTG-IgA.[Note: these are substances produced by your immune system that are directed or targeted against “self” tissue – meanng parts of your own body. After gliadin (the destructive part of the gluten protein) crosses the intestinal lining, a special enzyme called tissue transglutaminase binds to gliadin and takes off a portion of the protein. This portion is called glutamine. tTG antibodies are antibodies that are directed against the complex made up of gliadin attached to the tissue transglutaminase enzyme.
When positive this test is considered 90 percent sensitive at accurately diagnosing celiac disease because the presence of these antibodies correlates highly with the immune system attacking and destroying the intestinal lining, known as villous atrophy.
The test is not only sensitive (90%) but highly specific (98%), the latter meaning that it won’t tell you that you have celiac disease if you don’t. There is a “loophole” to the sensitivity feature however. Much damage needs to occur to the lining of the small intestine before this celiac disease test shows positive, making it a poor early marker for celiac disease. One doesn’t want to have to wait until they are at an advanced state of intestinal destruction. This test won’t show positive until damage is severe. Additionally not all celiac sufferers demonstrate villous atrophy and therefore this wouldn’t be the best celiac disease test for them. TTG- IgA is also not a test for gluten sensitivity.
Another liability to this most common celiac disease test is that typically only immunoglobulin A (IgA) is evaluated. IgA, a part of the immune system primarily found in mucous membranes, such as the small intestine, is the most sensitive for antibody testing, but only when a patient has normal functioning.
Total Immunoglobulin A, abbreviated total IgA, is an adjunctive test that should be done to prevent false negative test interpretation. IgA deficiency is 10 to 15 times more common among patients with celiac disease than in the general population. Thus, total IgA levels should be quantified in a separate “total IgA” test to ensure that IgA function is normal. If a deficiency is present, all tests utilizing IgA could be falsely negative, causing one to miss the presence of celiac disease or gluten sensitivity. Low IgA level s suggest inflammation of the intestinal lining and greater chronicity of disease. A low IgA level may provide some insight into duration of disease.
If IgA sensitivity is suspected or confirmed, measuring IgG in the form of a DGP test is the best alternative, or Cyrex Labs, mentioned below also offer great alternatives. Knowing this data is critical to ensure that you are not told that a test is negative when it’s a false negative.
DGP Celiac Disease Test
Deamidated gliadin peptide, IgA and IgG, abbreviated DGP – IgA/ IgG has a high specificity and is considered a useful test among patients who have selective Immunoglobulin A (IgA) deficiency.
EMA Celiac Disease Test
Endomysial antibody, IgA, abbreviated EMA-IgA. [Note: endomysium is a thin connective tissue layer that covers muscle fibers. These antibodies develop in reaction to damage to the intestinal lining. When the immune system attacks gliadin, it is not attacking “self” tissues but instead a foreign food protein. In contrast, as gliadin is absorbed through the intestinal lining, it attaches to the smooth muscle cells of the intestinal wall. EM antibodies are directed against proteins of these smooth muscle cells, and therefore EM antibodies are directed against “self” tissue. This defines them as auto-antibodies. Due to their attack of the smooth muscle of the small intestine, EM antibodies correlate better with damage to the intestine wall.]
Studies have supported an accuracy rate of approximately 90 percent for celiac disease. Actually in one study, EM antibodies were present in 100 percent of individuals when total villous atrophy was present, and therefore like the tTG test, it suffers from a lack of accuracy when only mild damage has occurred to the intestinal lining.
This is highly specific celiac disease test but it has variable sensitivity of 70 to 100 percent, due to the technical difficulty associated with performing the test. This liability associated with a higher expense makes it more of an adjunctive or follow-up test rather than a first line screening tool.
AGA Celiac Disease Test and Gluten Sensitivity Test
Anti-Gliadin Antibodies, IgG and IgA, abbreviated AGA –IgA/IgG. [Note: Gliadin, the most abundant protein in wheat, is part of the gluten protein (similar proteins are found in rye, barley). Gliadin is broken down in the intestine to segments of protein (polypeptides) called exorphins. These exorphins can be responsible for many of the “extra-intestinal” symptoms associated with gluten sensitivity as they can cross into the brain creating behavioral changes, outbursts, inattention, mania and other symptoms associates with schizophrenia, bipolar, ADHD and autism. According to Dr Davis, ingesting gliadin increases one’s caloric consumption by 400 calories per day!]
Antibodies to gliadin can bind to nervous system tissue and contribute to many of the neurological symptoms associated with gluten sensitivity such as ataxia, migraine, mood swings and more.
There is no official test that has been approved for testing gluten sensitivity, but many feel that AGA is one of the best we have and both IgA and IgG are tested. AGA isn’t typically used to diagnose celiac disease but it is recommended as a follow-up test to help ensure the celiac patients are following their gluten-free diet. A positive AGA test on a celiac patient can indicate poor adherence to the diet.
Genetic Celiac Disease Test
Genetic testing – a simple swab of the cheek can tell you if you carry the genes for celiac disease (HLA-DQ2 or HLA-DQ8). If you do not carry the genes it is impossible for you to ever develop the disease. Upon that point everyone is in agreement. However, beyond that there are some varying opinions. Many doctors point out that if you aren’t showing signs of the disease there’s no reason to implement a gluten-free diet. Personally I think having one gene, let alone two, is more than enough reason to embark on a gluten-free diet if you are experiencing any health issues. Of course following up a positive genetic test (there are some genes that are thought to predispose one to gluten sensitivity vs celiac disease and we often see patients who are clearly sensitive to gluten possessing one of each type. More research needs to occur in this area.) with available blood tests for both celiac disease and gluten sensitivity, along with the presence of typical symptoms and the improvement of said symptoms once a gluten-free diet is embarked on, all total to a valid diagnosis, without the need of an intestinal biopsy.
Anti-Reticulin Antibodies, IgA, abbreviated ARA-IgA. This test is not ordered as frequently due to its lack of sensitivity and specificity as compared to other autoantibodies. It is found in about 60% of celiac disease patients and about 25% of patients with dermatitis herpetiformis, the skin condition associated with celiac disease. When used, ARA is ordered along with other celiac disease tests as part of a panel.
Cyrex Labs – 11 Arrays. Saving the best for last, I want to mention Cyrex Labs that are fairly new on the scene as a lab but are, to date, offering some of the best insights to how a body is being affected by gluten, be it celiac disease or gluten sensitivity. The lab offers many “Arrays” that shed light on not only a reaction to gluten but secondary effects of gluten as well in the form of cross-reactive foods, leaky gut autoimmune tendencies and many more.
I mention this lab last as it is a specialty lab and therefore not available from most traditional medical doctors and I dare say that most gastroenterologists have likely never heard of them. But they provide excellent tools that are currently unavailable elsewhere.
6 Stories: Real People Write In for Help with Celiac Disease Test Interpretation
Below are some real life examples that have come to my attention via my blog and practice regarding a celiac disease test and what patients have had to endure regarding faulty interpretation of their tests.
“Was told I’m not celiac….But I feel horrible. Below is my celiac disease test, what do you think?”
First are my old results:
Gliadin Antibody IgG 31 – High Range Normal = <11
Gliadin Antibody IgA 6 – Normal = <6
Tissue Transglutaminase IgA <3 – Normal = <5
Then last year everything was pretty much the same but Gliadin IgG 23.4 High Range , Normal = <10
What does it mean and if I’m not celiac why does gluten seem to make me feel so horrible? Help!
It hurts my heart to see such things. To interpret, this gentleman tested positive for non-celiac gluten sensitivity years ago. His doctor interpreted his celiac disease test as negative for celiac, an evaluation with which I don’t disagree. However, and this is a BIG however, the doctor neglected to mention that his immune system was definitely having a negative reaction to gluten – something we call non-celiac gluten sensitivity (NCGS). Of course since he didn’t eliminate gluten his test continued to be positive, which we see in the later results.
The poor man feels horrible and it could have been completely prevented by correctly interpreting the celiac disease test correctly the first time.
Moral of the story: get the most comprehensive test you can. If you see anything abnormal, find someone who can correctly interpret the test. Don’t ignore what your body is telling you. If you need my help, I’m here for you.
Here’s another one:
My daughter recently had the following blood work results. These were ordered by her General Doctor as she was experiencing diarrhea. No other major symptoms. The results were/are:
Endomysial Ab IgA – Negative
Tissue Transglutaminase Antibody (tTG) 23 – Normal is 0-20.
She was advised that she is allergic to all glutens. Is that correct?
She has been referred for an endoscopic examination with a specialist.
Let’s look at this one. Realize this is a mom writing about her child so the phrase “allergic to all glutens” isn’t exactly correct, but that’s fine. Where the potential problem lies is in the outcome of the endoscopy test with the specialist. If it’s negative, is the specialist going to tell the mom that there isn’t any damage so therefore she shouldn’t subject her child to the rigors and severity of a gluten-free diet? I’ve seen that happen on many occasions.
The tTG test above is clearly positive and that indicates celiac disease. The child has diarrhea which is a classic symptom of celiac disease. If she removed gluten from her diet and was shown to have the genes for celiac disease, the outcome of the endoscopy would be moot. It would mean that four out of five necessary criteria for a celiac diagnosis would be met without the need for either doing the endoscopy or having a positive result.
Too often doctors are unaware of these criteria, which were published world-wide several years ago, by leading research experts from around the world in the area of celiac disease. About twelve different experts agreed on these criteria while also validating the presence of non-celiac gluten sensitivity as a valid condition.
I truly hope this child is put on a gluten-free diet before more damage can occur to her body.
Moral of this story: Do some research and know what it takes to receive a positive celiac disease test result, as well as a positive NCGS diagnosis. Actually your research is done right here by reading this blog! If you need more help, feel free to contact us through HealthNOW Medical Clinic San Jose.
Patricia V said…
I have been having stomach issues. I went for a blood test and this is the result of the celiac disease test:
Transglutaminase IgG <15
Transglutaminase IgA 27.3
Gliadin IgG: <15
Gliadin IgA <15
My primary Dr. said he thinks I might have Celiac Disease (and so does my mother). He wants me to make an appt with a Gastroenterologist. Just by the numbers (after all my research) it looks like Celiac. Transglutaminase is elevated – isn’t that indicative of Celiac? I am just confused by the “might” comment. Any thoughts?
I include this one as it is a classic example of something we see often. Now this particular patient is very pro-active. She did her own research and correctly, I might add, diagnosed herself. She’s correct, her test is highly indicative of celiac disease with the transglutaminase value (tTG) being elevated. As I mentioned in the previous example, many doctors don’t know that a biopsy doesn’t have to be positive in the face of adequate criteria that make the diagnosis of celiac disease.
Let’s imagine this patient wasn’t so pro-active. Let’s imagine she didn’t have the wherewithal to go to see a specialist – the gastroenterologist. What if the thought of seeing a specialist, let alone the cost of doing so was overwhelming to her? What if there was a 6 to 9 month (or more) wait to see the specialist? In other words, there could be many reasons a patient who very likely has celiac disease is not going to pursue it further. And because the doctor was keeping it all so vague, an individual could very likely leave with the idea that they “might” have something but since the doctor wasn’t emphatic they can brush it off.
If this sounds unlikely, let me assure you that I have run into this scenario more times than I’d like. The result is a person who becomes more and more ill from a disease that they later find could have been prevented by removing gluten from their diet. If they had only had their lab test interpreted correctly, they could have stopped eating gluten and prevented the development of a disease that is now shortening their life.
Here’s another real life example:
A woman had been previously diagnosed from her doctor with DH (dermatitis herpetiformis), a very unsightly and uncomfortable skin condition and a form of celiac disease. DH is absolutely known to be caused by gluten, yet this was never told to this patient. Fast forward a few years and this woman has now developed more health problems, specifically multiple sclerosis, an autoimmune disease of the nervous system.
Gluten is known to create autoimmune disease. Further, gluten is known to affect the nervous system more than any other system in the body, including the digestive tract..
Upon seeking help after her M.S. diagnosis, a smart doctor noted that she had DH and recommended a gluten-free diet. She is feeling better gluten-free but she now has M.S., a disease she could have avoided developing.
Can we state categorically that if she had eliminated gluten upon first being diagnosed with DH that she would not have developed M.S.? No, we can’t. But it does cause one to wonder what could have occurred if, once the “skin manifestation of celiac disease” (DH) was first diagnosed, a gluten-free diet was implemented.
The reader also asks if blood tests can be negative with DH. Yes they can and frequently are. Also remember that even those diagnosed with celiac disease via biopsy show negative blood results 15% of the time.
That’s why the moral of the story at this time is to evaluate how you feel when you eat 100% gluten-free for a couple of months. Until we have highly sensitive tests we can rely on to accurately diagnose gluten sensitivity, diagnosing will involve “building a case” by pulling together many pieces of information about the patient including symptoms, response to a gluten-free diet, lab tests, genetic history, presence of intestinal infections, etc.
This leads us to explain some things about this particular patient. She has known to have DH which is solely due to gluten, yet it can be present with negative blood tests. Does that make the diagnosis or need for a gluten-free diet in question? Not at all. She has now been diagnosed with MS. We know that, second to the digestive tract, the most common system to be affected by gluten is the nervous system, with autoimmune diseases occurring at a very high rate. Does the negative celiac disease test ensure that gluten had nothing to do with the development of MS? No, it doesn’t, since that often happens with DH patients. We’d need to know a lot more about this patient (which by the way is the most difficult part of hearing from readers long distance – I want more data.) but I wouldn’t be surprised to find other factors which point to gluten as the culprit.
Gluten sensitive patients not only have to do their own research regarding their symptoms but they have to self-diagnose and sometimes are forced to interpret their own lab tests!
What a sad story. I would like to say it’s unique and uncommon but unfortunately quite the opposite is true. The lack of understanding of the damage gluten can cause is staggering.
Another classic example
The next example is another classic example of where, in my opinion, our medical profession “falls down” when diagnosing celiac disease. The individual below has a positive celiac disease test, yet after 4 months on a gluten free diet, feels no better. As confused as she is, how long do you think she will continue the diet when she feels no better? Let’s take a look and then I’ll explain what is likely going on.
These are my test results:
Gliadin Ab (IGA) 49 units (<20)—[Is it very high? What would be the highest number?]
Gliadin Ab (IGG) 13 units(<20)
Endomysial Ab : Positive
Those were tests I had for celiac. Doctor told me to go on gluten free diet since tests are positive for celiac disease. But what does it mean that IGG is negative? And IGA 49 confirms celiac?
I didn’t have a biopsy performed. I am 4 months on gluten free diet and I am not feeling better. 🙁
It is the positive endomysial test that has caused her doctor to diagnose celiac disease. The AGA – IgA test is also positive, giving us strong evidence that her body is having a negative reaction to gluten. We humans are so funny sometimes. In an effort to justify why we can go against the result of a positive test, we ask “how positive is it’? It’s like getting a positive pregnancy test back and asking “how pregnant am I?” It’s an all or nothing proposition. When a test is positive it’s positive, period.
I further went on to explain to her that a body either has celiac disease or it doesn’t. There’s no such thing as ‘mild celiac’ or ‘a little celiac’.
With that said, I don’t blame her for questioning the diagnosis when she’s not feeling any better following the diet. This individual wrote in from a blog. Since she wasn’t a patient, I had no more data to hand than what was provided. But since the EM test is so highly accurate, it’s unlikely that Ada is not being negatively affected by gluten. The reason she doesn’t feel better likely lies in the area of the secondary effects of gluten that haven’t been addressed that are perpetuating her symptoms. I speak often on this topic, feel free to search the blog for more information.
When the total IgA results are low…
We mentioned earlier when reviewing celiac disease test options that a low IgA can potentially falsely affect test results. Below is such an example.
My results are:
Transglutaminase Ab (Iga) <3
IgA SERUM 52 low
C-reactive is high
Feel awful, weight gain, have high blood pressure, inflammation and pain.
When the total IgA results are low, any test utilizing that immunoglobin will be false. Therefore we cannot tell whether this person has a positive tTG or not. It’s too bad that the lab did not also measure IgG in the form of other tests. The high C-reactive protein shows inflammation, so it is important to figure out where that it coming from.
We definitely cannot state for sure that the individual has celiac disease but we do know that inflammation is present and something is overwhelming his/her IgA, a key constituent of the immune system. And of course we know that he/she feels terrible.
Having done this job for decades, what I too often witness is a patient such as this one walking away from such a celiac disease test result with the feeling that they: a) looked for a disease, b) it wasn’t found and now, c) they just need to “get used to” feeling terrible. It may sound silly but believe me it’s a very common occurrence. It makes me want to scream, honestly, but it happens a lot. Helping such people get to the root cause of their problem is what I specialize in.
The stable datum is that if the body is feeling terrible there IS a reason for it. Finding out the root cause of why is not terribly difficult when you know how.
We see patients local to our area, as well as those from across the country and internationally at our destination clinic where we get to the root cause of their problems.
If your health is not to the level you desire, whether it involves a celiac disease test or not, consider contacting us at HealthNOW Medical Clinic San Jose for a FREE CONSULTATION. Just call 408-733-0400 to schedule.
Dr. Vikki Petersen, DC, CCN, FMCP, a Doctor of Chiropractic and Certified Clinical Nutritionist, is founder of the renowned HealthNOW Medical Center in Sunnyvale, California. She is co-author of The Gluten Effect: How “Innocent” Wheat Is Ruining Your Health a bestselling book that has been celebrated by leading experts as an epic leap forward in gluten sensitivity diagnosis and treatment.
HealthNOW Medical Center serves San Jose, Sunnyvale, Cupertino, Mountain View – and all cities of Santa Clara and San Mateo counties.It is also a Destination Clinic, treating patients from across the country and internationally.
Functional Medicine Certified Practitioner
Founder of HealthNOW Medical Center
Author of “The Gluten Effect”
Author of eBook: “Gluten Intolerance – What You Don’t Know May Be Killing You!”