Serial Dilution Allergy Testing


A Fast and Effective Way to Control Allergies

Before discussing the Serial Dilution Testing, let us first review the common traditional skin allergy testing and see why such testing does not provide an optimum solution in most instances.  There are 3 most common traditional skin testing methods used to diagnose inhalant allergies:

I. Scratch Test:  Here the most superficial part of the skin is scratched and a strong extract is applied to the skin.  If you are sensitive to it, it may show a positive reaction.  There are a few problems with this test:

        i. This test is not as sensitive and as informative as we would like it to be.  This is because the superficial part of the skin is very  insensitive.  This means that to elicit a positive response from the skin, we have to use a strong concentration of the extract. Therefore, both false negative and false positive tests are likely - false negative because of relative insensitivity of the skin and false positive because of some irritant effect of the strong concentration.

        ii. When the test is positive, it is very difficult to quantify precise sensitivity because a definitely positive test may not differ much from a moderately positive test.  Therefore, when the allergist starts a patient on an allergy injection build-up, his goal is to start at a dilution that is far below than what could possibly cause a reaction in the patient.  This means that the physician may start  treatment at a dilution 1:100,000, 1:1,000,000 or even at a weaker level.  Suppose your treatment dose is at a dilution that is 1:50  and if you are started at a dilution 1:1,000,000, you can very well see how it may take 2 to 3 years to reach the maintenance dose.

        iii.  A third problem is that after the testing is completed, all allergens are put in equal dilutions since there is no way to know the precise relative sensitivity.  Therefore, even when time is given to build up to the proper dosage for certain antigens, one may  start reacting to some of the ingredients (allergens) while for others, the dose may still be low.  In other words, for some  allergens the dose may be right, while for others it may be too little or too much, causing reactions.

        iv.  In the interim period (which may be 2-3 years) before the patient has a chance to reach the maintenance dose, he has to  depend upon drugs to control the symptoms.


II. Prick Test:  Here a drop of strong extract is applied to the skin and then superficial layer of the skin is pricked through the drop.

The Scratch and Prick Test are about the same as far as the sensitivity is concerned.  Therefore, they have similar limitations. 


III. Intradermal Test:  Here, a small amount of the allergy extract is injected into the skin and a small wheal is made which looks like a small mosquito bite.  The deeper layer of the skin is far more sensitive than the most superficial layer.  Therefore, intradermal tests become far more sensitive than the superficial tests - Scratch and Prick Tests.  Moreover, because of the sensitivity of the test, you cannot test with strong extracts as you do with the other two tests.  Therefore, a much weaker dilution is needed to do the skin testing to avoid the reaction.  However, if your level of sensitivity is lower than the dilution at which the test is being performed, it will give a falsely negative test.  Moreover, the intradermal test does not give us a relative level of sensitivity since a definitely positive test may not differ much from a moderately positive test.  So intradermal testing with a single dilution is also of limited value.   



Now, let us discuss Serial Dilution Testing.  This is a modification of intradermal testing.  In the typical intradermal testing, as mentioned above, only one dilution is tested.  So, if you test with a dilution that is lower than the patient's level of sensitivity, the test is likely to show negative and if you test with a dilution that is far above the patient's actual level of sensitivity, it may cause a reaction.  To overcome this objection, Dr. Herbert J. Rinkel modified the intradermal test.  This modified testing is called "Serial Dilution Testing".  He made various dilutions of an extract and started testing intradermally, from the weaker to the stronger dilutions.  In doing so, he discovered the most sensitive, fast, and economical way of testing and treating inhalant allergies.  He found that when you test with a dilution that is below the patient's level of sensitivity, the skin will give a negative test and if you test with progressively stronger and stronger dilutions, and if the patient is sensitive to that allergen, it will show a positive wheal on a dilution that corresponds with the patient's level of sensitivity.  See Illustration # 1 that shows how various dilutions are made.


Illustration 1


These dilutions are made in a 1:5 dilution factor.  Therefore, bottle #9 (dilution #9) is the weakest and bottle # 1 (dilution #1) is the strongest dilution.  From this testing, we can find the relative sensitivity of each allergen and then we can start treating at the same dilution as the skin is showing a positive wheal.  For most allergens, the treatment dose will be found within the same dilution.  Therefore, one can actually


Start Treatment Dose at this dilution and reach the maintenance dose within 4-5 injections, i.e. 4-5 weeks, instead of taking 2-3 years to reach the maintenance dose.  After you are done with the testing, you do not need to start at a very low level, like 1:1,000,000, then go to 1:100,000, then 1:10,000, and then 1:1,000, etc.  If you are reacting at 1:100 dilution, or 1:500 dilution, we can start the treatment at those levels.  By testing this way, we overcome all of the objections that pertain to scratch and prick tests.  We find this test to be a very quick and effective way to control inhalant allergies because the sooner you reach the maintenance dose, the faster the relief.  This means feeling better, controlling symptoms, and getting off drugs such as antihistamines, decongestants, wheezing, cough medications, etc. 


Illustration 2


See Illustration # 2.  This is what the allergy testing sheet looks like.  The top numbers 1 through 9 show various dilutions of the extract and X shows where the patient's skin test became positive.  From this example you can see that this patient is reacting to dilution #2 on house dust, dilution #3 on house dust mite, dilution #5 on dog, and dilution #4 on cat.  Now we know the precise relative sensitivity of each allergen and we will start treating them on these levels.  This will provide highly individualized doses for each allergen, making it the quickest way to reach the maintenance dose and bringing relief to patient's symptoms and quickly reduce the need for drugs.


Illustration #3:  Serial Dilution Skin Testing for House Dust


In this illustration, the patient was tested on dilution #4 and #3, to which the test was negative and then the patient was tested with dilution #2, where the test became positive and on dilution #1, it became more positive.  This means that the patient will be started on the treatment program at dilution #2, which is 1:250 dilution; instead of starting at 1:1,000,000 and building and building weekly to reach this dilution. 


In a patient with just inhalant allergies (i.e. - those patients that do not have concomitant food or chemical sensitivities) a typical course of events is as follows:


*  1st injection may provide 1-2 days of relief.

*  2nd injection may provide 2-3 days of relief.

*  3rd injection may provide 3-4 days of relief.

*  4th injection may provide 4-5 days of relief.

*  5th injection usually provides 5-7 days of relief.


A dose that gives 5-7 days relief is the maintenance dose.  When you reach the maintenance dose, it provides the following benefits:


i.    It relieves the patient's symptoms, such as runny nose, sneezing, coughing, wheezing, difficulty in breathing, itching of nose, itching of eyes, watering of eyes, etc.


ii.   It reduces the need for medicines, often tremendously, such as the need for antihistamines, nasal sprays, wheezing medicines, bronchial sprays and other symptomatic therapy.





If you have hay fever, you know what it means -- in the pollen season any time spring through fall, you feel miserable with sneezing, running nose, watering eyes, coughing, wheezing, and itching.  While most people are enjoying the outdoors, you are trying to find refuge indoors.  Depending upon your pollen season, you may be miserable for 1-6 months out of the year.  Co-seasonal treatment means that when you come for the testing, you are already reacting to pollens and are having symptoms.  We test and treat the patient in the same season and provide relief in the same season.  In such a situation, the time can be cut even further to only 2 weeks.




We have thus far discussed serial dilution testing in relation to inhalants only.  The same technique can be applied to all other allergies, including foods and chemicals.


1.         Desensitization for foods:


Serial dilution testing establishes a treatment dose for foods called neutralization dose.  Once the testing is completed, the precise treatment dose has already been determined.  This treatment dose is called the neutralization dose.  This does not require any build-up.  Therefore, when you take your first dose, say a day after the testing, you have already reached the treatment of maintenance dose right there and then.  Desensitization for foods allows you to eat the foods you are sensitive to in small to moderate quantities which would otherwise make you quite sick.  For example, if you are allergic to common foods such as milk, egg, wheat, corn, sugar, yeast, and soy bean, it is really hard to avoid them.


2.         Desensitization for chemicals:


Similarly, the neutralization dose or a treatment dose can be established for common chemicals in our environment that make a patient sick and which are hard to avoid, such as perfumes, tobacco smoke, formaldehyde, cosmetics, auto exhaust, gasoline, cleaning products, etc.  This allows the patient to visit places where the patient may be getting sick, such as shopping centers and malls, restaurants, place of work, school, etc.


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