Which marker is used to assess CSF leakage and is also known as Prostaglandin D synthase?

• A. Immunoglobulin G
• B. Albumin
• C. Beta trace protein
• D. Total protein

Answer: (C)

Detecting CSF leakage is best done with a marker that is produced in the CNS and present at high levels in CSF but relatively low in other fluids. Beta-trace protein, which is prostaglandin D synthase, fits this role. This small protein is synthesized in the CNS and accumulates in CSF; when CSF leaks into nasal passages or wounds, beta-trace protein appears in the leaking fluid at higher concentrations than would be found from non-CSF sources. Measuring beta-trace protein in the suspected fluid provides a reliable indication of CSF leakage because of its CSF-specific abundance.

Immunoglobulin G is an antibody found in both serum and CSF, so it isn’t a specific indicator of leakage. Albumin is used mainly to assess the integrity of the blood–brain barrier (via the CSF/serum albumin ratio) rather than to detect leakage. Total protein in CSF is non-specific and lacks the selectivity needed for confirming CSF leakage.