Oral food challenge test of heated egg yolk in patients with an egg white allergy that tolerate 1 g of boiled egg white

Abstract

 Background : Egg yolk oral food challenges (OFCs) are frequently conducted as a replacement for small-amount egg white OFC. However, limited information is available regarding the amount of egg white remaining in egg yolk.

 Purpose : We evaluated the amount of residual hen's egg white in a raw egg yolk and investigated whether or not patients with an egg white allergy with a low threshold dose could consume one egg yolk.

 Methods : We separated an egg yolk using an egg separator and boiled it. Then, we weighed the egg white and vitelline membrane on the surface of the yolk. We selected 11 patients who tolerated 1.0 g of heated egg white based on the results of a heated egg white OFC from September 2014 to February 2015 and performed an egg yolk OFC.

 Results : The amount of egg white and vitelline membrane on the surface of egg yolk was 0.7 g (0.6-1.0 g, n=6). Of 11 egg-yolk OFCs, 9 showed negative results, 1 had local erythema, and 1 had multiple erythema.

 Conclusion : Eighty% of Patients who tolerated 1.0 g of heated egg white appeared to be able to consume one heated egg yolk.