Skin prick test for food allergies

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judy02
Regular Member


Date Joined Jun 2010
Total Posts : 126
   Posted 1/7/2011 6:12 AM (GMT -7)   
Hello everyone.
 
I was just wondering how reliable the skin prick tests are for detecting food intolerances? I already know I am intolerant to wheat, I was just wondering whether it is worth asking my doctor to do a skin prick test for any other food intolerances...
 
Are they the best type of tests to have? I know I probably sound stubborn, but I refuse to have any tests done where I have to consume a certain food for weeks or months on end for the test to be accurate. I have spent a long time being very sick by eating food that is bad for me...I refuse to make myself even more ill again! ;)
 
Just wondering what peoples experience is with the skin prick test, and if it is worth asking my doctor for further testing? I get a lot of digestive issues anyway, most of the time it is controllable by diet so just wondering what people think?
 
Thanks :)

Red_34
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Date Joined Apr 2004
Total Posts : 23549
   Posted 1/7/2011 6:45 AM (GMT -7)   
According to my daughter's allergist, the only test that can used (other then the food challenge test) is the RAST which is a blood test. And sometimes even then it's not reliable - for instance, my daughter is highly allergic to shell fish, but the blood test came back negative (hmm tell that to her skin!) and I am allergic to strawberries and hazel nuts, but my blood test came back negative as well even though my body reacts to those things. Sometimes it just about listening to your body instead of relying on the tests.
SHERRY
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S.E.F
New Member


Date Joined Jan 2011
Total Posts : 9
   Posted 1/7/2011 9:50 AM (GMT -7)   
I have never had the Prick test, sometimes you don't need too, just tell them what you know for sure that your allergic too. I told them i was allergic to hazel nuts, which they linked to a specific tree, then to some plants and now i have a whole list of things i should avoid. Sometimes, you just can't count on the tests alone, sometimes the specailist simply asks for details (like what reaction you recieved, for example a rash) and then they can link it to other allergies, symptoms and things to avoid.

-Lizzy

Alcie
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Date Joined Oct 2009
Total Posts : 4928
   Posted 1/7/2011 10:34 AM (GMT -7)   
I've had skin prick and RASTs, don't believe all of the results. I have no problem with peanuts, but show positive on skin test. But then I just read on a website (sorry I don't have the address) that all the tests are about 80% wrong. I think that may be an exaggeration too.

My allergist had me keep a food journal, with dates, times, everything I ate or drank and my symptoms. It helped me get together a list of foods I seemed not to tolerate. It took a couple of months!

Then she had me do food challenges at home. Note - I was not having life-threatening symptoms!!!
For milk, for example, I was to take a teaspoonful, then wait 20 minutes. If there were no symptoms I took 2 tsp and waited 20 minutes more. Then 4, and 8, and 16 which was the stoping point. Of course this was for immediate reactions. Some people get symptoms, like migraines, as long as 2 days after consuming a trigger food.

For some foods I consumed larger quantities to start, when I was sure I might react but not to such a small amount.

There are lots of foods and additives for which there is no test yet. My sensitivity happens to be sulfite, but others react to MSG and other preservatives, colors, flavors, etc.

Food sensitivities and intolerances often are quantity dependent, unlike "true allergies" like peanut, where the smallest dose creates a response.

Wheat allergy can be from celiac disease, which can be confirmed only by biopsy, but also it can be an acquired allergy as we get older. My PCP says he's known several patients who have become intolerant over the years he's seen them. I think I don't tolerate it well, as I feel better when I avoid breads.

I take allergy shots for my tree pollen, grass, dust and mold allergies. They work well for me and I have no symptoms now.
Alcie
 
 

RoseColoredGlasses
New Member


Date Joined Jan 2011
Total Posts : 4
   Posted 1/7/2011 10:54 AM (GMT -7)   
I've had the prick test, not just for food allergies but for basically everything, and it was not helpful and a complete waste of time. A friend of mine also has never had any allergies but then this summer was on a trip and came back covered in hives from head to toe and they didn't go away for about a week. He had never had them before so he had no idea what to do so he went to the doctor. His doctor made him an appointment at an allergist for OCTOBER! Over 2 months away! So he just stuck it out and they eventually went away. He thought that he must have been allergic to food because that was the only thing on the trip that he had never did/touched/etc before. He went to his appointment months later and first they yelled at him for not coming in sooner and then when they did the prick test suprise suprise no positive results. So now he has no idea what he is allergic to and has no way of knowing what to avoid. Needless to say...I hate doctors and the prick test.

judy02
Regular Member


Date Joined Jun 2010
Total Posts : 126
   Posted 1/7/2011 11:23 AM (GMT -7)   
Thanks for the replies everyone :)

Razzle
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Date Joined Aug 2007
Total Posts : 4399
   Posted 1/10/2011 10:01 AM (GMT -7)   
Alcie,

If bread bothers you but pasta or cake don't, then you may have a yeast intolerance/sensitivity...

I have antibodies to yeast (both brewer's yeast and baker's yeast), and I notice that I don't feel well in my stomach when I eat yeast-containing bakery goods.

Comments on the testing for food allergies:

Skin test result accuracy depends on the concentration and age of the test serums used. The test serums are not standardized, so you may react at one doctor's office, but not at a different doctor's office if they each use different test serum concentrations. Also, the proteins in the test serums can break down over time, rendering them unable to elicit an allergic response even in individuals with known severe allergies to what's being tested. If a person has anergy, then they won't react on a skin test...anergy is caused by an imbalanced immune system (commonly seen in those with certain autoimmune disorders). This is why they have to put the histamine and saline controls on you when they do the skin test...if no reaction is seen to the histamine (i.e., anergy), then they know the test isn't going to be valid. Also, if a person is taking antihistamines, then this test will likely not be accurate. Blood allergy tests and the other tests mentioned below are not vulnerable to the effects of antihistamines.

Blood tests (RAST, CAP-RAST) can miss allergies for the same reason as skin tests can. And also they can miss allergies because the tests are designed to detect one configuration of protein for a given food but there may be many different configurations (i.e., different protein configurations of the allergenic proteins in the food) or possible proteins.
 
My allergist explained it like this...say a wheat protein looks like your hand. The RAST or CAP-RAST blood test may be able to detect an antibody that sticks to the thumb, but not to any of the fingers on the wheat protein. So if a person's wheat antibodies aren't "thumb-shaped" then their wheat allergy test won't detect their allergy to wheat, even though an oral challenge proves the allergy.

There are other tests less well-accepted:

Blood ELISA IgG/IgA/IgM allergy tests (not sure if these are FDA-approved yet or not, but there has been a lot more research on this type of testing recently, especially in the setting of Irritable Bowel Syndrome). These test for delayed hypersensitivity to foods. I've had such tests done twice (IgG testing is most common, but the others are available from certain labs) and got slightly different results both times. They tell me these tests aren't accurate if the person isn't eating the food tested regularly, but I have antibodies showing up on these tests for foods that I haven't eaten in years (example = oats...I get very nauseated from oats, and haven't eaten oats in over 5 years, but I test positive on the IgG & IgM for oats). Unfortunately, the labs doing these tests often don't test foods that are not eaten commonly...such as arrowroot, millet, etc., so if you already eat a non-traditional diet, the test may not be as useful.

ALCAT tests (I don't think these are FDA-approved for allergy testing). Another blood test that can detect supposedly any kind of antibody to foods. I have not had this testing done, so I don't know much about it.

Electro-Dermal Screening. Not FDA-approved for allergy testing, but this testing method can reveal intolerances, hypersensitivities, & allergies. The premise of the test is that acupuncture meridians will show energy flow changes when the person is in contact with the foods that cause their body to experience problems. I personally think this method is more subjective than blood testing for allergies, but also it is not limited by the available test foods - you can be tested for any food you can hold in your hand.

A variant of EDS is applied Kinesiology testing (muscle-testing) - also not FDA-approved for allergy testing. It is used in conjunction with NAET by some practioners. The premise is the same as for EDS, except instead of a machine measuring energy flow on a specific acupuncture point, the practitioner pushes on the patient's arm while the patient tries to resist and this is done while the patient is holding the test food in their other hand. The theory is that the muscles used to resist the pushing on the arm will go weak in the presence of foods that are not "healthy" or "beneficial" for the patient. I think this method is more subjective than the EDS method of testing, but it does not require special equipment to perform, and thus can be used in a grocery store when one is looking for something new to try.

Another variant is dowsing - also not FDA-approved for allergy testing. The person holds the test food in their left hand, and the practitioner touches the person's right side (shoulder or hand, usually) and swings a pendulum to "dows" for whether the food is compatible or good for the person or not. Some think this is a little too out there for them, but one of the advantages to this method is, if you have a good dowser, it can be very accurate. Also, if the dowser has a "witness" (film photograph, writing sample, piece of hair, etc.) of the person, they do not have to actually be present for testing to occur...so it can be done remotely.
Stool testing (EnteroLab.com - I have no financial connection with this company) - a new form of allergy testing is looking in the stool for antibodies to certain foods.  This type of testing is very new, and not much is known about the limitations of this type of testing.  I got my Gluten-Sensitivity diagnosis from this method, and they also were able to test for egg, yeast & dairy sensitivities.

I've experienced all of the above except ALCAT, and the testing that I find most accurate is dowsing and EDS. Both methods have told me that there are only a few foods in existance that don't bother my body in some way or another.

Take care,
-Razzle

Chronic Lyme, Bart., Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut dysmotility & non-specific inflammation, UCTD, Osteoporosis, etc.; G-Tube
Meds: Ceftin, Singulair, Claritin, Domperidone, Milk Thistle, homeopathy, probiotics, etc.

Post Edited (Razzle) : 1/10/2011 10:05:58 AM (GMT-7)


Alcie
Veteran Member


Date Joined Oct 2009
Total Posts : 4928
   Posted 1/10/2011 6:27 PM (GMT -7)   
Interesting comments Razzle -
I rarely eat any pasta or cake because they usually go along with sauces and icings I know I don't tolerate. I'll have to go through my notes, maybe try challenge testing some pasta. I'm OK with pita bread that doesn't have additives, when I can find any.

For me, the most accurate way to figure out if I don't tolerate a food is to keep a food journal, recording symptoms an hour or two after eating. then I challenge test the components of a suspect meal.
Alcie
 
 

Chicagorunner
New Member


Date Joined Dec 2010
Total Posts : 17
   Posted 1/14/2011 9:42 AM (GMT -7)   
I also have had negative results on skin tests when I know the particular food causes a reaction. There are times when you are not "allergic enough" for it to show up. I think keeping the food journal is a good way to go, but you also have to watch all the additives and it can get confusing and difficult to weed everything out. Or, go with more organic to weed out the chemicals, but then the cost goes up.

Razzle
Veteran Member


Date Joined Aug 2007
Total Posts : 4399
   Posted 1/14/2011 3:54 PM (GMT -7)   
Yeah, and organic doesn't guarantee it is free of additives, either...there are some "allowed" additives in organic stuff...such as copper sulfate as a fungicide on grapes...
-Razzle

Chronic Lyme, Bart., Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut dysmotility & non-specific inflammation, UCTD, Osteoporosis, etc.; G-Tube
Meds: Ceftin, Singulair, Claritin, Domperidone, Milk Thistle, homeopathy, probiotics, etc.
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