Test: Oral Food Challenge - Cow's Milk

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Background/Purpose

Oral food challenge (OFC) is the gold standard for diagnosis of IgE-mediated and non-IgE mediated food allergy. It is usually conducted to make diagnosis, to monitor for resolution of a food allergy, or to identify the threshold of responsiveness. Clinical history and lab tests have poor diagnostic accuracy, and they are not sufficient to make a strict diagnosis of food allergy. Higher concentrations of food-specific IgE or larger allergy prick skin test wheal sizes correlate with an increased likelihood of a reaction upon ingestion. Several cut-off values, to make a diagnosis of some food allergies (e.g., milk, egg, peanut, etc.) without performing an OFC, have been suggested, but their use is still debated. The oral food challenge should be carried out by experienced physicians in a proper environment equipped for emergency, in order to carefully assess symptoms and signs and correctly manage any possible allergic reaction.
The value of performing the OFC should be determined,
taking into consideration the risk and benefits of undergoing the
OFC. As outlined in the previous report, an OFC is useful for
identifying foods causing reactions in the following situations1:
1. Serum IgE testing and/or skin prick test (SPT) results are not
consistent with the patient history.
2. When the family/patient and physician agree that the risk
estimated from the medical history and the test results (see
Table E1 in at www.jaciinpractice.org) is outweighed by the benefit of possibly adding a food to the diet.
3. Determining whether food allergens associated with chronic
conditions such as atopic dermatitis (AD) or eosinophilic
esophagitis will cause immediate reactions.
4. Expanding the diet in persons with multiple dietary
restrictions.
5. Assessing the status of tolerance to cross-reactive foods.
6. Assessing the effect of food processing on food tolerability (eg,
fruits and vegetables that may be tolerated in cooked form in
patients with pollen food allergy syndrome [PFAS]).

Procedure

It is best that the patient have nothing but sips of water for two hours prior to the challenge. Avoid, if
possible, giving the patient anything to eat/drink for 4 hours prior to the challenge. If this is not
practical, a small meal 2 hours prior is okay. Try to have the patient arrive hungry. If there is already
food in the stomach, it may make it more difficult to eat the "challenge" food and may delay the
absorption of the "challenge" food.
During the challenge, a regular serving of food (base on age) will be used.
The "challenge" food is eaten in small, increasing doses. The patient will be closely observed for any
sign of an allergic reaction. Emergency medications to treat a reaction are immediately available, if
needed.
It takes approximately 60-90 minutes to complete the feeding portion of the food challenge. The
patient will then be observed for an additional 1-2 hours or more after eating the food. The food
challenge typically takes about 4-5 hours. If a reaction occurs, we may observe the patient for a longer
period of time before discharge. We ask that you plan your day to ensure adequate time to remain at
the clinic for observation if a reaction were to occur.
Performed: Bilaterally

Dialog

The patient is closely monitored for reactions as food samples are administered to the patient.

Criteria

• No or minimal reaction to samples.

Measurement

LOINC Code

Scale/Grading

selection range; grade - LOINC ID
Option - Value option selection range; grade - LOINC IDPass ; Pass - Fail ; Fail -