Quantification of beta-trace protein and detection of transferrin isoformsin mixtures of cerebrospinal fluid and blood serum as models of rhinorrheaand otorrhea diagnosis

Different mixtures from a serum pool and a cerebrospinal fluid (CSF) pool w ere used as models to study CSF contamination in secretions by determining two CSF specific proteins: beta-trace protein (beta-TP) and the asialo-tran sferrin (a-Tf) band which was detected by isoelectric focusing (IEF) with T f specific immunofixation. beta-TP and total Tf were measured immunonephelo metrically. Secretion/serum ratios of beta-TP content > 2.0 indicated CSF c ontaminations with greater than or equal to 5% (v/v) CSF; this was confirme d by detecting the a-Tf band by IEF. Reliable a-Tf bands were only revealed with secretion/serum rations of Tf contents < 0.1, indicating an interfere nce of major sialo-Tf fractions with the a-TF band detection in the sample. For CSF detection in rhinorrhea and otorrhea, complementary use of beta-TP assay and a-Tf assay is recommended. Preanalytically, dilution or concentr ation of the sample as well as denaturation of Tf and beta-TP should be pre vented by optimizing sample collection.