Margie - I'm surprised your nutritionists would say that after "flirting" with gf diet that your test would be POSITIVE - I'd have thought the other way around because you'd lessened the offending agent.
Here's an explanation of some test results per Dr. Green in his book, Celiac Disease: The Hidden Epidemic:
IgA Endomysial Antibodies (EMA)
Testing for EMA ishighly specific, virtually 100 percent so, and about 90 percent sensitive. If this test is positive, it means that virtually 100 percent will have celiac disease, though some patients with celiac disease may not be positive for EMA. Nevertheless, these antibodies correlate to the degree of villous atrophy. (See Selective IgA Deficiency, below.)
This is a test done using immunofluorescence technique. It's expensive and is read manually by a technician using a microscope. Therefore, it is observer dependent, which introduces an element of potential technician error.
There are some physicians who beieve that the EMA test, when properly conducted, is as good as an intestinal biopsy for the diagnosis of CD. There is not the same degree of trustin the tTG.
Unfortunately, there may be a stage when the IgA EMA test is negative in a patient, only to appear and test positively two or three years later. (See Latent Celiac Disease.) This is often seen in clinical practice. These people probably had celiac disease but were not diagnosed because those antibodies were negative. EMA may also be absent in patients younger than two yrs of age.
Doctors must rely on tests to give them an indication of a problem, and often it is necessary to retest if patients' symptoms continue. ALSO, SEROLOGICAL TESTS, IN CLINICAL PRACTICE, OFTEN LACK THE SENSITIVITY REPORTED IN THE MEDICAL LITERATURE.
IgA Tissue Transglutaminase (tTG)
tTG is the enzyme that converts gliadin into a more toxic molecule. At the NIH Consensus Dev. Conference in 2004, it was generally agreed to be one of the key serologic markers for celiac disease.
Yet, the tTG antibody is not 100 percent specific - there are other causes of its being positive, and they include diabetes, heart failure, and liver disease. Also, people who have CD can have a negative tTG test.
This is an automated test. It is an ELISA - an enzyme linked immunosorbent assay - that is machine read from a kit that the lab buys. The kit contains the "substrate" to which the blood sample is added - in this case usually human tissue transglutaminase. This process sets off a reaction that is interpreted by a machine as a number that falls into a postive or negative range.
The test is done with different kits at different labs, and results may vary. (See Laboratory Differences, below.)
IgA and IgG Antigliadin Antibodies (AGA)
IgA and IgG antigliadin antibodies arise in the intestine and circulate in the blood. They are seen as a reaction to the ingestion of gluten. THEY MAY BE SEEN IN CONDITIONS APART FROM CELIAC DISEASE AND ARE, THEREFORE, NOT HIGHLY SPECIFIC FOR CD. They may also be seen in people with NO detectable diseases. You can have positive results for these two tests and not have CD.
The antigliadin antibody tests were the first serology tests for CD and have outlived their usefulness. Their major role is following compliance to the diet. They will disappear from the bloodstream more rapidly than EMA or tTG after starting a gf diet. New generation antigliadin antibody tests may be available in the future and show good results for the diagnosis of CD.
Selective IgA Deficiency
There is a genetically determined condition called selective IgA deficiency that occurs in about 0.2 percent of the population and in about 3 percent of patients with CD. These people do not make IgA antibodies, whether or not they have CD.
Since most of the highly specific and sensitive blood tests for CD measure IgA, the tests are measuring a class of antibody that some people cannot ever make. Therefore, if a patient's total IgA is 0 or extremely low, running an IgG tissue transglutaminase antibody is recommended in order to determine if IgG celiac antibodies are present. These tests are important if you are IgA deficient since you may not be otherwise be diagnosed.
I'll type up what Sensitivity and Specificity, Lab Differences and False/Negatives/False Positives later.
KNOWLEDGE = POWER. BODY = TEMPLE. FOOD = MEDICINE. PREVENTION IS THE CURE. YOU ARE WHAT YOU ABSORB!
One person's food is another person's poison.
Celiac Disease: An autoimmune reaction from eating gluten grains: wheat, rye, barley and contaminated oats=nutrient deficiency=cancer. Have 1 of 300 symptoms? bit.ly/cdsymptoms
CD stories: bit.ly/cdstories
|2,958 Days since: gluten