The purpose of this study was to determine the cutoff value for sIgE in house-dust mites and animal dander and to analyze differences in cutoff value according to age and gender.

Sixteen thousand two hundred nine patients with more than one allergic rhinitis symptom who underwent both SPT and serum sIgE testing were retrospectively evaluated between March 2008 and May 2012. The criterion standard for allergen sensitization was defined as a wheel of >3 mm or an allergen-to-histamine ratio of ≥1 in SPT results. The researchers used the Youden index to calculate the cutoff value of sIgE.

Cutoff values of sIgE for Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat, and dog were 0.69, 1.16, 0.13, and 0.45 kU/L, respectively. The cutoff value of sIgE changed according to age for D. pteronyssinus and D. 

The cutoff value for sIgE differed for each antigen and changed with age. According to antigen and patient age, physicians should select the proper cutoff value for sIgE for appropriate criteria rather than using a constant cutoff value.