Peanut Allergy: Testing Update

June 29, 2010

Peanut allergy is generally confirmed through allergy skin testing and/or blood testing looking for peanut specific IgE.  Usually someone suspects that they or their child is allergic to peanuts because of specific symptoms that have occurred with exposure, and testing is done to confirm the diagnosis.  

There are situations however, where a child is tested for peanut allergy with either a skin test or a blood test because they have other food allergies and the parent is concerned about the possibility of also having peanut allergy.  Often this occurs before the child has ever eaten peanuts.  If this kind of testing comes back positive, it means that the child is making allergen antibody (IgE) against peanut, but it does not necessarily mean that the child will have clinical symptoms upon exposure.  

A recent study has provided some insight into what percentage of children with positive testing and no history of an allergic reaction to peanuts, actually have clinical allergy to peanuts.  The study did allergy testing in a cohort of children followed from birth.  The study found that 11.8% of children in the cohort had positive testing for peanut allergy.  An extensive analysis of the children with positive testing, including further testing and oral challenges, revealed that 22.4% of those with positive testing and no history of  having a reaction to peanuts, actually had clinical peanut allergy.  So, from this study, we can expect that about 1/4 of children who test positive to peanuts before ever consuming peanuts, will have true clinical peanut allergy.    A supervised challenge in a doctor’s office would need to be done in order to determine if a child is really clinically allergic.  Not all children are candidates for a challenge however.  This would be determined by the allergist based upon an evaluation of the skin or blood test results.  Depending on the level of positivity of the results, some children would not be considered for a challenge.

Peanuts consist of several different allergens.  The testing that is usually done commercially looks at peanut specific IgE, but does not test for each specific peanut allergen.  The study mentioned above looked at each separate peanut allergen and tried to correlate specific peanut allergens with clinical peanut allergy.  The study found that those children with positive testing to the peanut allergen called Ara h 2 were most likely to have clinical allergy.  Less than 10% of children with positive peanut specific IgE on general blood testing who could consume peanuts without having a reaction, had positive antibody testing to Ara h 2.  These results do need to be confirmed, but they are extremely interesting in that they point toward more specific testing for allergens yielding more specific answers with regard to the clinical relevance of a positive test.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Sunscreen Update

June 17, 2010

The Environmental Working Group (EWG) recently released its 2010 sunscreen guide.  The EWG is a not for profit environmental organization that specializes in environmental research and advocacy in the areas of toxic chemicals, agricultural subsidies, public land and corporate accountability.   Among other things, the EWG is working to pass the Kid-Safe Chemical Act which would require that industrial chemicals be safe for infants, kids and other vulnerable groups.  The 2010 sunscreen guide is the 4th such guide the organization has released.  The full report can be found on www.ewg.org/2010sunscreen/.

After reviewing the evidence, the EWG determined that of all types of sunscreens on the market today, mineral sunscreens have the best safety profile since they are stable in sunlight and do not appear to penetrate the skin. Additionally they offer UVA protection which is often lacking in most of today’s sunscreen products.  Mineral sunscreens are those containing micronized zinc and/or titanium.  See my April 2, 2010 blog post entitled Sunblock For Sensitive Skin for more information on these types of sunscreens. 

An important bit of information the EWG included in their report is a recommendation for children to not use oxybenzone.  There are many products on the market that contain oxybenzone.  Some of those products are specifically marketed for children.  The following is directly from the EWG report: “Scientists have called for parents to avoid using oxybenzone on children due to penetration and toxicity concerns.”

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Allergy Shots Part 5: Children And Allergy Shots

June 11, 2010

Although allergy shots are effective at any age, I generally do not consider allergy shots as a treatment option until after 7 years of age.  The reason for this is that I think prior to that age it is difficult for children to fully understand why they are getting weekly shots and I fear that the potential psychological trauma may out way the benefits.   

There is reason to believe that the earlier allergy shots are started the more significant the benefits.  Allergy shots may prevent the development of new allergies in children who are allergic to one or two allergens.  It is not unusual for a child to first develop allergies to tree pollen and then over time develop allergies to other pollens or dust mite.  Alternatively, a child can first develop allergies to dust mites or cockroach and then over time develop various seasonal pollen allergies.  Allergy shots may also prevent the development of asthma in children who are receiving shots for nasal allergies.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Allergy Shots Part 4: What Results Can I Expect?

June 10, 2010

The main positive affects of allergy shots are not felt until maintenance is reached.  It is generally possible however to get an idea of how effectively a patient is becoming desensitized by noting how they respond to the allergy shots.  If a patient is able to tolerate increasing doses of allergens without having significant local reactions at the site of the injections and without having more generalized allergic reactions to the shots, then that patient is becoming desensitized.  Maintenance doses are large doses of allergen that would definitely result in significant allergic reactions if administered to an allergic person prior to undergoing the build up desensitization phase.

Each person clinically responds to allergy shots in a slightly different way.  The best case scenario is complete desensitization with elimination of the allergic response to the allergen.  The best example of this is a patient with tree pollen allergy who comes in for a monthly maintenance shot in early May and has no allergy symptoms and is on no medications and asks me if the tree pollen season has started.  I am always thrilled when this happens since by early May in New York, people with tree pollen allergy have usually already been suffering with symptoms for several weeks.  Some people have this kind of response.  Others have a less complete desensitization in that they still have some symptoms, though less severe than before starting allergy shots and more easily controlled with fewer medications.

Unfortunately, it is not possible to predict in advance how well a specific individual will respond.  However, it is important for the doctor to determine for sure that a person is truly allergic to a specific allergen and that the allergy is responsible for the symptoms BEFORE starting allergy shots.  If the allergy is not causing the symptoms, allergy shots for that allergy will not help at all.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Allergy Shots Part 3: How Are They Administered And What Are The Side Effects?

June 9, 2010

There are two phases to allergy shots, the build up desensitization phase and the maintenance phase.  Patients are initially started on very low doses of the allergen, and during the build up phase the doses are increased to higher and higher levels until the maintenance dose is reached.   It usually takes about 24 visits to get to the maintenance dose level and these visits are usually weekly or twice a week.  Once the maintenance dose level is reached, the visits are spaced to every 2 to 4 weeks. 

Since allergy shots actually contain the substance that you are allergic to, the main potential side effect is an allergic reaction to the shots themselves.  Because of this possibility, all people on allergy shots, must wait in the doctor’s office for 30 minutes after the shot is given so they can be monitored for the possibility of a reaction.  It is not unusual to have a little itchiness or slight swelling at the site of the shot.  The type of reaction that is concerning and needs to be treated immediately, is a more generalized allergic reaction to the shot, including anaphylaxis.  There have been rare reports of life threatening anaphylaxis resulting from allergy shots.  I always emphasize the importance of waiting a full 30 minutes after receiving a shot since that is the time frame within which the vast majority of reactions will start to occur.  

I prescribe an Epi Pen for all of my patients on allergy shots and ask them to carry it with them the day of their shot.  An Epi Pen is a self-administered shot of epinephrine or adrenaline that is carried routinely by people with life threatening reactions to foods or bee stings.  I think it is a good idea for people on allergy shots to have this with them the day of their shots as an extra level of caution.  Fortunately, I have never had a patient on allergy shots who has had to use an Epi Pen for that purpose.

Patients will sometimes ask me if it is OK for them to administer shots to themselves at home.   The answer to that is simple: NO.  It is never appropriate for allergy shots to be administered outside of a physician’s office or health care facility that is prepared to treat anaphylaxis. 

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Allergy Shots Part 2: What Types Of Allergies Have They Been Proven To Effectively Treat?

May 26, 2010

There have been many studies evaluating the effectiveness of allergen immunotherapy or allergy shots.   The most rigorous scientific studies are those that are placebo-controlled and double-blinded.  A placebo-controlled allergy shot study is a study where some patients receive actual allergy shots and some receive injections of saline placebo.  A double-blinded, placebo-controlled allergy shot study is a study that is placebo-controlled and neither the patient nor the physician knows who is getting the allergy shot and who is getting the saline placebo.

Double-blind, placebo-controlled clinical studies have proven that allergy shots improve the quality of life, reduce symptoms and reduce the need for medications in children and adults with the following allergic conditions:

1. Nasal and ocular allergies (Allergic Rhinitis and Allergic Conjunctivitis)

2. Allergy-related asthma

3. Bee sting allergy:  All people who have experienced life threatening reactions to bee stings should be on allergy shots to help prevent these reactions in the future.

Allergy shots have been proven to work for grass pollen allergy, tree pollen allergy, weed pollen allergy,  mold spore allergy, allergy to animals such as cats and dogs, cockroach allergy and dust mite allergy.

Other benefits of allergy shots:

1. About 1/3 of patients with allergic rhinitis (nasal allergies) eventually develop asthma.  Allergy shots can decrease the risk of developing asthma for someone who only has nasal allergies.

2. Someone with an allergy to one allergen, such as dust mite, is at an increased risk of developing an allergy to another allergen, such as tree pollen.     Allergy shots for one allergen can prevent a person from becoming allergic to other potential allergens.

3. Allergy shots can be effective for atopic dermatitis or eczema that is associated with allergy to aeroallergens such as dust mites or pollens. 

4. Some studies have shown that allergy shots might help with the oral allergy syndrome.  (see Tree Pollen Allergy and Foods: The Oral Allergy Syndrome; 4/9/10)

Allergy shots are NOT effective for food allergy and should not be used for hives or angioedema.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Allergy Shots Part 1: What Are They? How Do They Work?

May 25, 2010

Allergy shots, or allergen immunotherapy, is the only FDA approved treatment available to make someone less allergic to a specific allergen.  All other FDA approved therapies for allergies are directed at controlling symptoms.  Allergen immunotherapy is directed at changing the immune response.  Allergen immunotherapy administered with shots is the only FDA approved method in the United States.   There is a lot of ongoing research on administering allergen immunotherapy through droplets under the tongue (sublingual immunotherapy).  This form of immunotherapy is used in Europe.

The purpose of the immune system in general is to protect the body against microorganisms (germs) and act as scavengers within the body to remove defective, dying or abnormal cells.  The allergic arm of the immune system directs itself against otherwise harmless substances such as dust mite or tree pollen with an allergic immune response mainly mediated by the allergen antibody called IgE.    When an allergen and a specific IgE against that allergen is present in an allergic individual, the IgE binds to cells in the immune system causing the immediate release of allergic mediators such as histamine and leukotrienes.  This causes immediate symptoms and initiates a larger and more progressive allergic immune response.  Allergy shots work by changing the immune response away from an allergic immune response. 

There are many complex changes that occur within the immune system with successful allergen immunotherapy.  It is important to note that the changes are very specific and do not affect other aspects of the immune system.  The various changes are as follows:

1. Shifts the immune response toward a non allergic response to the allergen. 

2. Generates specific regulatory immune cells that induce immune tolerance, or a decrease in the immune response, toward the allergen.

3. Induces the production of non allergen antibody called IgG toward the allergen.  These antibodies can block the allergen antibody (IgE) from releasing mediators such as histamine, that are responsible for allergic symptoms. 

4. Blocks the immediate and late phase allergic response.

5. Decreases the recruitment of inflammatory cells that contain mediators to the nose, eyes and lungs. 

6. Decreases the rise in allergen antibody that occurs in allergic individuals during the allergy season. 

Many people think of allergen immunotherapy as a more natural approach to the treatment of allergies since it utilizes the allergens themselves to induce immune changes.  That might be true, but it is important to point out that allergen immunotherapy is NOT a homeopathic approach to allergies.  Homeopathy is based upon treatment using minute quantities of substances.  Allergen immunotherapy starts with minute quantities of allergen, but doses are gradually increased and it only really works when high doses called maintenance doses are administered. 

Stay tuned for more information on allergen immunotherapy. 

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


FDA Announces “Bad Ad Program”

May 13, 2010

The FDA announced yesterday a new program called the “Bad Ad Program” designed to help health care providers detect and report misleading drug advertisements.  When I read about the new program it immediately brought to mind the various antihistamine advertisements touting how a particular drug works against outdoor and indoor allergens.  The ads basically imply, without specifically saying, that one antihistamine works for all types of allergies whereas another might only work for indoor allergies and another for only outdoor allergies.  I have had many patients ask me if a particular drug that seemed to be working for pollen allergy would also work for indoor allergies such as cat or dust mite allergy. 

The bottom line is histamine is a mediator that is responsible for many of the symptoms of allergies.  If a person is allergic to an allergen and has allergen antibodies (IgE antibodies) circulating in their system directed against a particular allergen, histamine is released by cells in response to the allergen.  Antihistamine medications act against this histamine release regardless of the allergen that is causing the problem.   Antihistamines work for histamine release caused by a food allergy, medication allergy, pollen allergy, dust mite allergy or pet allergy. 

It is completely misleading for a pharmaceutical company to create an ad highlighting the fact that their antihistamine works against indoor and outdoor allergens, since all antihistamines work against indoor and outdoor allergens.  Now, you may ask, how is it that one company can include this in their ad and another can not.  Well, that is actually the FDA’s fault.  The FDA approves each medication for a specific indication.  If the drug company does efficacy studies on an antihistamine using outdoor and indoor allergens, the FDA will approve the medication for both.  If the drug company’s efficacy study for a particular antihistamine only involves pollen, the FDA approves the drug specifically as only being indicated for seasonal pollen allergies (or outdoor allergies) and not indoor allergies.  This does not mean the medication does not work for indoor allergies, and the FDA should know that.  The problem is, drug companies are only allowed to include in their ads information pertaining to the specific FDA approved indication of the medication.   

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Air Purifiers

May 11, 2010

There are lots of different air purifiers on the market and I will often be asked by patients which air purifier is the best.  First off, it is important to make a differentiation between HEPA filtered air purifiers and the rest.  I recommend HEPA filtered air purifiers to my patients.  They work by filtering out very small particles from the air as the air passes through the filter.  The size of the unit you need depends on the size of the room.  If the window or door to a room is open, the air purifier will not be as efficient in filtering the air in the room.  

I think the best brand is IQAir.  Unfortunately, it is also the most expensive.   There are units you can purchase that contain a carbon filter in addition to a HEPA filter.  Carbon filters help remove odors and chemical pollutants from the air.

I do not recommend that you buy any air purifier that produces ozone.  Many of these types of air purifiers have electrostatic panels that you wash, instead of HEPA filters that need to be changed.   Although they often only emit small amounts of ozone, why emit ozone into your home if you don’t need to?

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.


Food Allergy And Skin

May 3, 2010

There are many in the medical profession who do not think food allergy is a major cause of eczema/atopic dermatitis.  That might be true for adults, but about 37% of children with eczema have at least one food allergy.  If you look at the statistics in reverse, you find that about 90% of children with food allergy have eczema.   In general, it is worthwhile to do food allergy testing on an infant or young child with severe eczema.  If a particular food is identified,  a trial elimination diet should be pursued to determine the impact of the elimination on the condition of the skin.

Another skin condition associated with food allergy is hives.  Hives can occur suddenly in an otherwise well person.  This form of hives is called acute hives.  If hives last more than 6 weeks they are called chronic hives.

A food can be identified as the cause in about 20% of cases of acute hives.  In this setting, if food is responsible, it generally occurs within minutes to 1-2 hours consumption of the food.  A detailed history will often reveal one or more suspect foods and allergy testing should be done to verify whether or not a person is allergic to any of those foods.

When a person has chronic hives lasting more than 6 weeks, a much smaller percentage have an associated food allergy.  Only about 4% of children with chronic hives have a food allergy and about 1.4% of adults with chronic hives have a food allergy.  Whether or not it is necessary to do food allergy testing in the setting of chronic hives depends on the patient’s history.

Note: The content of this blog is for informational purposes only and is not meant as specific medical advice for a specific person.   If you have a medical problem, please contact your doctor.