Beta-2 transferrin: limitations of use as a clinical marker for perilymph.

Beta-2 transferrin is a protein marker that can be used in the clinical setting to reliably identify the presence of cerebrospinal fluid (CSF). Recent literature has suggested that beta-2 transferrin can also be used as a clinical marker for perilymph. This study investigates the use of a beta-2 transferrin assay as a method to identify the presence of perilymph. Twenty-two patients were enrolled in the study. Fluid samples were obtained intraoperatively and tested for the presence of beta-2 transferrin. As expected, four CSF samples collected were positive for beta-2 transferrin; however, four known perilymph samples collected from patients undergoing cochlear implantation were negative for beta-2 transferrin, seven of nine known perilymph samples obtained during stapedectomies were negative for beta-2 transferrin, and four of five samples collected during middle ear explorations for fistula were negative for beta-2 transferrin. With current methodology beta-2 transferrin does not appear to be a reliable clinical marker for perilymph in the operative setting.