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Detection of spinal fluid in body fluids, such as ear or nasal fluid
The diagnosis of cerebrospinal fluid (CSF) rhinorrhea or otorrhea (leakage of CSF into the nose or ear canal, usually as a result of head trauma, tumor, congenital malformation, or surgery) is often difficult to confirm. Traditional chemical analyses (eg, glucose, protein, specific gravity) are unreliable. Radiographic studies, especially those involving the injection of dyes or radiographic compounds, are costly and may introduce additional risks to the patient.
Transferrin that migrates in the beta-1 electrophoretic fraction (beta-1 transferrin) is found in most body fluids. Beta-2 transferrin is a CSF-specific variant of transferrin and is used as an endogenous marker of CSF leakage. Beta-2 transferrin is formed by loss of sialic acid due to the presence of neuraminidase in the central nervous system. Beta-2 transferrin has also been called CSF-specific transferrin and tau protein.
Prompt diagnosis and localization facilitates appropriate decisions and decreases the risk of meningitis.
Negative, no beta-2 transferrin (spinal fluid) detected
The cerebrospinal fluid (CSF) variant of transferrin is identified by its unique electrophoretic migration. If beta-1 and beta-2 transferrin are detected in drainage fluids, the specimen is presumed to be contaminated with CSF.
The presence of beta-2 transferrin band is detectable with as little as 2.5% spinal fluid contamination of body fluids.
Beta-2 transferrin is also found in aqueous humor and in serum of patients with rare metabolic glycoprotein disorders or genetic variants of transferrin.
Beta-2 transferrin may be undetectable if the specimen is diluted by saliva and not frozen after collection.
Mayo studies comparing this immuno-enzyme detection method to our previous immunofixation-silver stain method indicate that the immuno-enzyme method is 10-fold more sensitive, as well as faster to perform (2.5 hours versus 4.5 hours).
1. Oberascher G: Cerebrospinal fluid otorrhea--new trends in diagnosis. Am J Otol 1988;9:102-108
2. Normansell DE, Stacy EK, Booker CF, et al: Detection of beta-2 transferrin in otorrhea and rhinorrhea in a routine clinical laboratory setting. Clin Diag Lab Immunol 1994;1:68-70