Food Allergy in a Toddler

Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at LSU (Shreveport) Department of Allergy and Immunology

A 2-year-old girl is referred to an allergy and immunology clinic for food allergy. Four months ago, she ate a cashew nut-containing candy and had an immediate lip swelling which required a dose of Benadryl.

She was placed on a strict nut dietary elimination. Her pediatrician prescribed an EpiPen Jr. for emergency use and ordered an ImmunoCAP titer for food allergens with a panel which included eggs, milk, wheat, corn, peanuts, soy, crab, shrimp, orange, and tuna. Significantly elevated allergy antibody titers were seen with peanut and egg white, and mildly elevated titers were seen with milk, wheat, soybean, and orange. The egg and peanut titers were sufficiently high to predict definite allergy, whereas the other low positive titers had a low probability of association with clinical allergy. Unfortunately, no tree nuts were obtained in that panel.

She had been consuming milk and wheat-containing products without any reaction. Currently, she is being maintained on an egg, peanut, and nut-free diet, and has had no further allergic reactions.


Peanut-containing products. Image source: Wikipedia, public domain.


Egg. Image source: Wikipedia.

Past medical history (PMH)

Intermittent night cough for 2 months which is present without signs of upper respiratory tract infection. She does have occasional runny nose but no sneezing or itching is reported. She also has occasional eczematoid rash to a mild degree with sparse red plaques which may appear in her elbow and knee creases intermittently.

She has a negative allergy history for any other food or medication allergies, a negative history for previously diagnosed asthma or allergic rhinitis. Immunizations are up to date with no reactions.

Medications

Multivitamins.

Family medical history (FMH)

Well-controlled asthma present in her mother

Social history (SH)

Home environment has no pets or smokers. She is in a daycare setting and the staff maintains the strict dietary elimination of nuts, peanuts, and eggs. She does have moderate to heavy dust mite exposure with a carpeted bedroom and regular mattress.

Laboratory results

Figure 1. RAST titer for food allergens.

Physical examination

VSS.
Skin: no rashes, keratosis, excoriations, or lichenifications.
HEENT: normal. Eyes had no conjunctival injection or swelling, ears had no fluid or inflammation behind the TMs, nose had no mucosal edema or discharge.
Chest: CTA (B).
CVS: Clear S1S2.
Abdomen: Soft, NT, ND, +BS.
Extremities: no c/c/e.

What is the most likely diagnosis?

The patient has a significant history of tree nut allergy in the context of positive family medical history. The egg and peanut RAST titers were sufficiently high to predict definite allergy.

Night cough could be due to asthma or GERD. The occasional rash affecting the elbow and knee creases can be a manifestation of atopic dermatitis.

What diagnostic tests would you suggest?

Skin testing.

Allergy skin testing was performed to house dust mites as well as tree nuts, and she did show strong reactions to all tree nuts tested, especially to cashew nut, pistachio nut, pecan, and walnut, and moderate reactions to almond and hazelnut. House dust mite was completely negative.

What happened?

This 2-year-old girl has a clinical history of significant tree nut allergy, and skin test evidence of significant sensitization to tree nuts. She also has significantly elevated RAST titers to egg and peanut.

We recommended strict dietary elimination of these foods in all forms, and that the family be vigilant to read labels for ingredients that may indicate the presence of these allergens in her diet.

She should continue to keep EpiPen Jr. available for emergency use in case of a severe reactions related to accidental food allergen ingestion.

She was prescribed a a trial of nebulized albuterol to be given up to every 4 hours PRN cough or wheeze, and gauge its effectiveness in relieving her cough. If this does prove effective, we will likely need to add an asthma controller agent such as inhaled corticosteroid. Should this prove totally ineffective, then we may wish to pursue evaluations for other causes of night time cough such as chronic sinusitis, or GERD.

For the mild eczema, she may use 1% hydrocortisone cream b.i.d. to any areas of redness or inflammation as needed.

A follow-up evaluation in 6 months was scheduled.

What is the likelihood of outgrowing allergies in later life?

Ninety percent of infants allergic to milk and 50 percent of those allergic to eggs outgrow their clinical reactivity by the age of 3 but most patients allergic to peanuts or cod do not.

Final diagnosis

Food Allergy in a Toddler

What did we learn?

Diagnostic algorithm for food allergy: SAD Child:

1. Symptoms: close relation between specific food intake and symptoms, often affect 2 or more organs
2. Allergy testing: skin prick testing or ImmunoCAP.
3. Diagnostic diet: restricted diet leads to symptoms disappearance or significant reduction
4. Challenge - oral food challenge.



Comparison of diagnostic methods for peanut, egg, and milk allergy - skin prick test (SPT) vs. specific IgE (sIgE) (click to see the spreadsheet). Sensitivity of blood allergy testing is 25-30% lower than that of skin testing, based on comparative studies (CCJM 2011).

References: Clinical review: ABC of allergies, Food allergy. BMJ 1998;316:1299, figure.

Eight top allergens account for 90 percent of all food allergies. The 8 top allergens can be remembered by the mnemonic TEMPS WFS:

Tree nuts (almonds, cashews, walnuts)
Egg white (not egg yolk)
Milk
Peanuts
Shellfish (crab, lobster, shrimp)
Wheat
Fish (bass, cod, flounder)
Soy


Figure 2. Food allergy mind map.

Only treatment is avoidance of the offending food (TEMPS WFS).


Figure 3. Eight top allergens account for 90 percent of all food allergies.

There is no current active treatment for food allergy. Traditional injection immunotherapy (SCIT) has been proved unsafe, and therefore there is a need for other forms of immunotherapy. Studies of oral immunotherapy (OIT) are currently conducted.

Remission of peanut allergy can be predicted by low levels of IgE to peanut in the first 2 years of life or decreasing levels of IgE sensitization by the age of 3 years.

What is a suggested approach for testing in a child with suspected peanut allergy by history?

Do skin prick testing for common food allergens at the time of the initial visit. Ensure the antihistamines were stopped at least 5 days prior to testing and there is no skin rash in the area to be tested. Do not do RAST initially because skin prick testing is both more sensitive and clinically relevant.

If the skin prick test is positive, check RAST in one year and yearly after that. Do not consider a food challenge unless the specific IgE level is less than 1. The lowest level is less than 0.1 but this is a "false basement," i.e. a lab "zero" is not the same as clinical "zero." A patient may have a specific IgE level of less than 0.1 and still react to peanuts on exposure.

The reported IgE values on RAST range from 1 to 100. If a patient has a history of allergic reaction to peanuts and IgE level is 5, he has a 100% chance of clinical reactivity. If the IgE level is 1, there is a 40% chance of clinical reactivity. If the IgE level is less than 0.1, there is a 25% chance of clinical reactivity. There is no clinical "zero" from the RAST which can guarantee "zero" chance for clinical reactivity.


Relative sensitivity of RAST, skin prick testing and intradermal testing. Image source: Adapted from Dr. Hopp, Creighton University Division of Allergy & Immunology, used with permission.

There are predetermined levels of specific IgE on RAST below which a food challenge can be attempted. Those levels are shown in the grid below:


Levels of specific IgE on RAST below which a food challenge can be attempted. Image source: Dr. Hopp, Creighton University Division of Allergy & Immunology, used with permission.


8 top allergens account for 90 percent of food allergies. Specific IgE levels (sIgE) that predict the likelihood of passing an oral food challenge are shown in the figure. (click to enlarge the image).

References

Food Allergies. eMedicine, 2006.
IgE and Non-IgE-Mediated Food Allergy: Treatment in 2007. M. Chehade. Current Opinion in Allergy and Clinical Immunology. 2007;7(3):264-268 (free Medscape registration required).
Food Allergy Clinical Resources. Health Sciences Library, The University of Alabama.

New Rules for Food Allergies - WSJ - Check the illustration showing what not to do vs. what to do: http://goo.gl/QNXZT
10-minute consultation: Food allergy. BMJ 2002;325:1337.
Clinical review: ABC of allergies, Food allergy. BMJ 1998;316:1299, figure.
New Guidelines Issued for Food Allergies. Medscape, 2006.
Manifestations of Food Allergy: Evaluation and Management. AFP, 1999.
Food Allergy: A Short Review. V. Dimov, AllergyCases.org, 2007.
About Food Allergies. ACAAI, Patient information.
Food Allergies--Just the Facts. AFP, Patient information, 1999.
Early clinical predictors of remission of peanut allergy in children. JACI, 03/2008.
Food Allergen Avoidance. V. Dimov, Oct 2008.

Audio and Video

Food Allergy and Additives. Presented by Sami L. Bahna, MD, DrPH. ACAAI Vodcasts 2007 (video).
AAAAI: Gradual Exposure Reduces Kids' Peanut Allergy. MedPage Today, 03/2008 (video).

Published: 07/06/2007
Updated: 01/03/2011