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.<ref>,

 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, 
 2004,
 Vol. 27(Issue: 1),
 pp. 39–42,
 DOI: 10.1016/S1015-9584(09)60242-6,
 PMID: 14719513,</ref>

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.<ref>,

 Beta-2 transferrin assay in clinical management of cerebral spinal fluid and perilymphatic fluid leaks, 
 J Otolaryngol, 
 
 Vol. 22(Issue: 5),
 pp. 341–4,
 
 PMID: 8283502,</ref>