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 fistula is suspected.
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 Cerebrospinal fluid fistula or a perilymph leak.
The effect of time and temperature on beta-2 transferrin stability in cerebrospinal fluid (CSF) is not well established. After collecting nasal CSF for testing, beta-2 transferrin has been found to be stable and detectable for 1 week, whether being refrigerated or stored at room temperature. The purpose of a study was to determine if beta-2 transferrin remained detectable longer than 1 week and whether refrigeration improved its detectability.
In patients undergoing therapeutic CSF diversion, 2-mL CSF samples were collected from 18 patients. The samples were divided and stored either at room temperature, or at 4°C, and tested for beta-2 transferrin at 7 and 14 days. CSF was collected from external ventricular drains (EVDs) (n = 15), lumbar drains (n = 2), and subdural drains (n = 1).
Of the 18 CSF samples originally testing positive for beta-2 transferrin, none turned negative at 7 or 14 days, in both the refrigerated and room temperature groups (95% confidence interval [CI], 0% to 18.5%).
Beta-2 transferrin remained detectable for 14 days in all CSF samples, regardless of being stored at 4°C or room temperature 1).