HOUSTON CELIAC SUPPORT GROUP

Janet Y. Rinehart, Chairman                                                                         281 / 679-7608

13722 Ashley Run                                                                         E-mail: txjanet@swbell.net

Houston, TX  77077                                                                         Celiacs Helping Celiacs

                                                          Chapter #25, CSA/USA, Inc.

 

 

 

 

CELIAC TESTING PROCEDURES

 

Now that more family doctors and gastroenterologists are more aware about the prevalence of Celiac Disease being up to 1% of the U.S. population, family physicians or internists may first think about a diagnosis of Celiac Disease for a patient.  He/she may first order the screening blood tests. However, it is important to use a laboratory that is experienced and reliable and has conferred about test standards with appropriate institutions.  (For a list of the experienced “national” laboratories, ask chairman Janet Rinehart.) After doing the screening blood tests, the family physician should refer the patient to a gastroenterologist specialist for further testing.

 

An endoscope procedure down into the small intestine should be done by a gastroenterologist.  This is the “gold standard” of diagnosis.  Regarding the endoscopic biopsy procedure, be aware that multiple samples (8-12 or more) from various parts of the small intestine are best for evaluation because Celiac Disease is a “patchy” disorder.  The skill and experience of the pathologist in orienting and analyzing the tissue on slides are factors that enter into the final diagnosis in the laboratory. 

 

One should be liberally eating gluten at least 5-8 weeks or more before the testing procedure, otherwise the tests may be falsely negative.  Therefore, one should not “try out” the diet before appropriate testing.

 

Dermatitis Herpetiformis

People with suspected Dermatitis Herpetiformis (the skin manifestation of Celiac Disease) should go to their dermatologist for testing.  He/she will take a biopsy of skin tissue next to a lesion (not the lesion itself).  If the results of the immunofluorescence test prove positive, then that person automatically has Celiac Disease as well.  Gluten is causing the skin damage.  Dapsone is one medication used for temporary cessation of the itching; it does not “cure” DH. Only a gluten-free diet will cure DH and CD.

 

A person with DH need not have the antibody tests listed below unless he/she wants to, although such tests may indicate the level of small intestinal damage.  Similarly, the endoscopic biopsy procedure.  If you have DH, you definitely have Celiac Disease, although the level of gut damage is probably less. Most likely you won’t have to have the endoscope procedure because you already have the diagnosis of CD concomitant with Celiac Disease.  The main treatment for DH is a strict gluten-free diet.  DH’ers tend to heal more slowly than true celiacs.  Celiacs seem to see reduction in their symptoms during the first 2 to 6 weeks, although complete healing may take up to a year.  The DH lesions take more time to heal, which happens to be an individual issue, unfortunately. 

 

Treatment

After proper diagnosis, the next step is to inform the patient that the only treatment is a gluten-free diet.  Good results on a gluten-free diet confirm the diagnosis.  A celiac must adhere to a strict gluten-free diet for life!   A knowledgeable dietitian may give an initial overview of the gluten-free diet.  Local and national celiac support groups give current and extensive material about the gluten-free diet.  The diet seems to be difficult at first, but it is quite healthy and the celiac does get used to it.  It is much easier to do the restrictive diet with help from the local support group.

 

 

Screening Blood Tests:

A doctor will order a “celiac panel” of blood antibody tests. Again, for these tests to be accurate, the patient must be liberally ingesting gluten (possibly 3 weeks to several months in advance and during all the testing procedures).

 

Any commercial laboratory would be able to obtain a patient's sample of blood and send it to the laboratory of your choice for processing. Obviously, such a local laboratory may require an additional fee to be paid to them for the processing and shipping.

 

Call a lab in advance to ascertain the protocol involved: how much blood to draw, whether it needs to be “spun down,” and any instructions for shipping.  These screening tests only tell the status at that point and time; they do not tell about what results will be in the future.  Also, these tests tend to show medium- to late stage Celiac Disease, not necessarily early stages of CD.  You may need to have them redone later.

 

Our physician advisor Alberto Barroso, M.D. suggests that first the total IgA level is measured, because if someone is IgA deficient, results from the panel of celiac blood tests might come back negative, which might be the wrong answer in terms of Celiac Disease.

 

 (1 & 2) Antigliadin antibodies (IgA and IgG) are two of the tests, but both are less sensitive and specific than the EMA and/or tTG tests. (The reticulin antibody (IgA) is out of vogue because other more reliable tests are available.)  New from the NIH Conference, Antigliadin antibody (AGA) tests are no longer routinely recommended because of their lower sensitivity and specificity.  Serologic testing for celiac disease in children less than 3 years of age may be less reliable and requires further study.

(3) The Endomysial antibody test (EMA IgA) (the most sensitive and specific - over 95% accurate). 

The EMA should be an immunofluorescence test; tTG is the specific protein that is identified by the IgA-EMA).  Dr. Michele Pietzak, gastroenterologist at Childrens Hospital in Los Angeles, told our support group in February 2004 that the EMA test was a better indicator than the tTG. 

(4) An additional test called Tissue Transglutaminase (tTG-IgA & IgG) also looks at the same antibody as the EMA test.  However, the EMA is subjectively analyzed by a person, where the tTG is done with a machine (which tends to be more reliable). 

(5) Again, the Total Serum IgA should be another test because most of the antibody tests are based on the IgA factor.  Someone with IgA deficiency could show  false negative results incorrectly. 

 

The total combination of these 5 tests are considered the most specific and sensitive for Celiac Disease. Be sure to get a copy of the full laboratory report so that you can see the results in relation to the positive ranges.

 

The University of Chicago Celiac Disease Center now recommends (6/05) only doing the Serum IgA (to test for IgA deficiency) and tTG (tissue transglutaminase) tests to screen for Celiac Disease. Also, they recommend Prometheus Lab (1-888-423-5227) and The Mayo Clinic lab as being the most experienced and reliable to analyze these tests. Quest is also up to speed now and this lab is usually on most people's insurance.
See University of Chicago Celiac Disease Center updated website at www.celiacdisease.net and especially the Fact Sheet on Antibody Screening for Celiac Disease, and other important topics.

           

The celiac panel of blood tests are largely for purposes of screening relatives of known celiacs.  The endoscopy biopsy is the "gold standard" of diagnosis for Celiac Disease.  The third part of the diagnosis is good results on the gluten-free diet.  Again, It is essential for correct results that prior to and during the blood tests and biopsy procedure, one must be on a gluten-containing diet.

 

These celiac antibody blood tests may not be reliable for children under the age of 3 or more.  According to pediatrician Dr. Alessio Fasano, Co-Director of the University of Maryland Center for Celiac Research, children's immune systems may not be mature enough to exhibit these antibodies, resulting in false negatives.  When tests come back positive, however, it is important to follow through with the biopsy procedure. 

 

#    One of the more experienced labs, Prometheus Laboratories  will send you a free test kit to take to your doctor.  Call Toll Free (888) 423-5227 or go to www.prometheus-labs.com .  They are located on 5739 Pacific Center Boulevard, San Diego, California 92121.  The company is completely focused on gastrointestinal diseases, with particular expertise in Inflammatory Bowel Disease and Celiac Disease. Genetic testing for certain celiac HLA markers is now available.  Also, a test for lactose intolerance is available.

           

#    An interesting site about the blood tests is at http://www.celiac.com/frequent.html#probability   

This is part of the research of the University of Maryland Center for Celiac Research.

 

#   Another site to look at about the serology tests is: http://www.fastlane.net/homepages/thodge/DIAG-TST.txt 

             

#    (“Current Approaches to Diagnosis and treatment of Celiac Disease: An Evolving Spectrum” by  Drs. Fasano & Catassi, Gastroenterology, 2001, Vol. 120, pages 636-0651)

#    Compile your complete medical history, including all medications you are taking, both over-the-counter, prescription, and vitamin supplements. When you go to any new doctor, take this medical history with you for your file. Be sure to get a copy of any and all medical tests.  Keep these always for your records. Make copies for any new doctors you may go for a second opinion.

 

#    The IgA and tTG are also used to test for compliance on the gluten-free diet for diagnosed celiacs

 

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Updated 26Sep07