Preliminary study on the stability of beta-2 transferrin in extracorporeal cerebrospinal fluid.

OBJECTIVE Detection of beta-2 transferrin in rhinorrhea fluid is a sensitive and specific method for the diagnosis of a cerebrospinal fluid (CSF) leak. Patients may be asked to collect this fluid at home to obtain an adequate volume for detection, and thus the age and storage conditions of these specimens may be variable upon analysis. The purpose of this study is to understand how age, storage temperature, and exposure to mucus affect the ability to detect beta-2 transferrin in CSF. STUDY DESIGN Case series with planned data collection. SETTING Tertiary care university hospital. SUBJECTS AND METHODS This study consists of 6 patients undergoing endoscopic CSF leak repair. CSF was collected directly from a lumbar drain (n = 4) or from nasal drainage (n = 2). Specimens were stored at 4°C (n = 3) or room temperature (n = 3). Samples were tested for the presence of beta-2 transferrin for up to 7 days using standard immunofixation electrophoresis techniques. RESULTS Beta-2 transferrin was detected in all specimens through day 7 regardless of storage temperature or collection site (95% exact binomial confidence interval of 0%-46%). CONCLUSIONS Beta-2 transferrin remains detectable in extracorporeal CSF for up to 7 days regardless of storage at room temperature or exposure to nasal mucus. Negative detection in patient specimens up to a week old is therefore not likely to be caused by protein degradation.