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Case History - Section 1
An adverse reaction to food is best referred to as food hypersensitivity. However, when immunological mechanisms have been demonstrated the appropriate term is food allergy.
When the role of IgE has been demonstrated, the term is IgE-mediated food allergy.
This case history focuses on IgE-mediated food allergy from infancy to 16 years of age.
James is now 16 years old.
He first presented at 8 months with severe atopic eczema (atopic dermatitis).
James was born full term and was breast fed exclusively for 6 months.
Atopic eczema commenced at 6 weeks and became generalized and severe. He was a colicky, unsettled baby.
Solids were introduced at 6 months beginning with rice cereal with some cow's milk formula.
His atopic eczema worsened significantly at this stage.
Answer: Skin prick test and/or allergen specific IgE in serum
THIS IS CORRECT - Well done: When testing for food allergy, fresh food material and the prick - prick method is best. There is no lower age limit for performing the skin prick test. Previously a lower age limit of 3 years was wrongly recommended.
A positive reaction is defined as a mean wheal diameter that is at least 3mm larger than the negative control.
Skin prick tests should not be performed on areas with active eczema, or areas treated with steroid or immunomodulator ointment.
Use of short acting antihistamines should be avoided for at least 3 days and use of long acting antihistamines should be avoided for 7 days in children prior to the skin prick test.
Quantitative measurements of allergen specific IgE in the serum (serum specific IgE) have a high reliability. The specificity and sensitivity are within the range of 85-95%.
Detection of serum specific IgE reveals sensitization to suspected allergens, and is a useful aid in allergy diagnosis since only those sensitized can develop IgE-associated allergic disease. Like the skin prick test, it must be related to the clinical history.
For further information on allergy investigations in children, access the statement of the Section on Pediatrics of the European Academy of Allergy and Clinical Immunology below:
Go to Case history - Section 2