Specimen Information

Type

2 containers:
Blood: Gold top (SST) tube -plus- Fluid (Aural or Nasal): sterile plastic tube with tightly fitting lid

Volume

2.0 mL Serum - plus - 2.0 mL Aural or Nasal Fluid

Transport Info

Blood:
- Clot 30 minutes
- Promptly centrifuge 15 minutes
- Immediately transfer serum to separate plastic tube
Fluid: Refrigerate container

Refrigerate both specimens

Fasting Required?

False

Clinical Significance

Detection of a beta-2 transferrin band by IFE is diagnostic for the presence of cerebrospinal fluid (CSF). This test is a consideration in the differential diagnosis for CSF otorrhea or CSF rhinorrhea. Beta-2 transferrin is not detected in normal serum, tears, saliva, sputum, nasal, aural fluid, or endolymph by this method.

The leakage of CSF into nasal or oral cavities and its subsequent drainage from these cavities may be caused by trauma, intracranial surgical procedures, infection, hydrocephalus, congenital malformations, and neoplasms. The CSF leakage most commonly presents as otorrhea or rhinorrhea. Chemical analysis of the fluid for glucose and protein is unreliable as a means of determining if the fluid is CSF. Radiographic studies, with or without intrathecal injection of dye or radioisotope, are not always successful in demonstrating small or delayed CSF leaks. Electrophoresis of fluid from a suspected CSF leak combined with immunofixation to detect transferrin has been shown to be both a sensitive and specific method of detecting CSF. Two isoforms of transferrin are present in CSF. One band is seen normally in serum and migrates in what has been termed the beta-1 (ß-1) protein fraction. The slower isoform in CSF results from modification of the protein by cerebral neuraminidase and migrates in the beta-2 (ß-2) fraction. Detection of beta-2 transferrin band by IFE is diagnostic for the presence of CSF. This test is useful for the differential diagnosis for CSF otorrhea or CSF rhinorrhea. Beta-2 transferrin is not detected in multiple fluids including normal serum, aural fluid, nasal secretions, saliva, tears, sputum, or endolymph. In addition, the beta-2 transferrin protein assay by IFE methodology is not a reliable method for detecting human perilymph due to the low sensitivity of the assay.