Beta-trace protein as sensitive marker for CSF rhinorhea and CSF otorhea.

OBJECTIVE Beta-trace protein concentrations in cerebrospinal fluid (CSF), serum and nasal secretions are investigated with a new quantitative, immunonephelometric assay. RESULTS The mean beta-trace concentration of normal lumbar CSF (18.4 mg/l) and normal serum (0.59 mg/l), from n = 132 control patients, were 10% higher than reported earlier for smaller control groups. The reference range of beta-trace protein in nasal secretions is very low (median: 0.016 mg/l, range <0.003-0.12 mg/l, for n = 29 controls). Clinically confirmed cases of CSF rhinorhea (n = 20) showed beta-trace concentrations between 0.36 and 53.6 mg/l, with a median of 2.4 mg/l. We propose a cut-off value of 0.35 mg/l above which a CSF contamination in the secretion is plausible. A clinically confirmed CSF otorhea had a value of 1.75 mg/l. CONCLUSION This new beta-trace protein assay offers a fast, sensitive and reliable routine method to detect a CSF rhinorhea or otorhea.