Nigel Turner wrote:
We have a wound exudate specimen from a patient who had a spinal
operation 2 weeks ago. It is a straw coloured fluid, squeezed from a
dressing, Total volume about 6ml.
The question posed is : Is this CSF ?
An interesting question, but not simple to answer definitively, since even
if this fluid contains CSF, it may not be pure CSF. Off the top of my
head, a "quick and dirty" test would be a total protein. Since the protein
concentration in "normal" CSF ranges from 5-45 mg/dL, the finding of a much
higher protein concentration (i.e., in the g/dL range) would be more in line
with some other exudate. Referring to Tietz's Textbook of Clinical
Chemistry (2nd edition, p. 723), if you perfom protein electrophoresis
(after concentrating the fluid), you should see a prominent band for
prealbumin and TWO transferrin bands if the fluid is CSF. The second Tf
band (called the "tau" band) is due to a sialic-acid-deficient form of
transferrin that is produced or transformed intrathecally. Hope this helps
- good luck!
Sal
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Salvador F. Sena, Ph.D., DABCC
Associate Director, Clinical Chemistry and Toxicology
Department of Pathology and Laboratory Medicine
Danbury Hospital
Danbury, CT 06810
Tel 203-797-7705
Fax 203-731-8061
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