Beta 2 Transferrin
CSF leakage may be caused by head trauma, cancer, congenital malformation or surgery. The diagnosis of rhinorrhea or otorrhea is difficult to confirm by conventional laboratory tests or radiographic studies. Prompt diagnosis and localization of the source of leakage decreases the risk of meningitis and facilitates treatment decisions.
Serum contains beta-1 transferrin and cerebrospinal fluid contains beta-1 and beta-2 transferrins. The central nervous system contains neuraminidase that partially desialylates beta-1 transferrin to form beta-2 transferrin. Beta-2 transferrin can be used as a biomarker of CSF leakage. Aqueous humor also contains beta-2 transferrin.
Beta-1 and beta-2 transferrin are distinguished by electrophoresis on a high resolution 1% agarose gel, followed by immunofixation with anti-transferrin antibody that is labeled with horse radish peroxidase. The presence of both beta-1 and beta-2 transferrin bands indicates the presence cerebrospinal fluid. This method is sensitive enough to detect the presence of spinal fluid when it comprises only 2.5% of a body fluid.
Preferred specimen is 0.5 mL of otic or nasal fluid in a plastic vial. Alternatively, a saturated cotton swab can be submitted if direct collection is not feasible. It should be transported in a tightly stoppered tube.
Reference range is a negative result, meaning that no beta-2 transferrin was detected.
