Archive for June, 2010

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.