Beta-2 transferrin

Beta-2 transferrin is a carbohydrate-free (desialated) isoform of transferrin, which is almost exclusively found in the cerebrospinal fluid. It is not found in blood, mucus or tears, thus making it a specific marker of cerebrospinal fluid, applied as an assay in cases where cerebrospinal fluid leakage is suspected.^[1]

Beta-2 transferrin would also be positive in patients with perilymph fluid leaks, as it is also present in inner ear perilymph. Thus, beta-2 transferrin in otorrhea would be suggestive of either a CSF leak or a perilymph leak.^[2]

References

1. Chan D, Poon W, IP C, Chiu P, goh K (2004). "How useful is glucose detection in diagnosing cerebrospinal fluid leak? The rational use of CT and Beta-2 transferrin assay in detection of cerebrospinal fluid fistula". Asian Journal of Surgery 27 (1): 39–42. doi:10.1016/S1015-9584(09)60242-6. PMID 14719513.
2. Skedros DG, Cass SP, Hirsch BE, Kelly RH (Oct 1993). "Beta-2 transferrin assay in clinical management of cerebral spinal fluid and perilymphatic fluid leaks". J Otolaryngol 22 (5): 341–4. PMID 8283502.