How can the nurse determine if drainage from a head injury is cerebrospinal fluid?

• A. Measure the pH of the fluid.
• B. Measure the specific gravity of the fluid.
• C. Test the fluid for glucose.
• D. Test the fluid for chloride.

Answer: (C)

Cerebrospinal fluid contains glucose, so checking the drainage for glucose is the most informative way to distinguish a CSF leak from other types of wound or sinus drainage. If glucose is present, it strongly supports that the fluid is CSF, since most other drainage fluids do not have significant glucose. Normal CSF glucose is typically about two-thirds of the serum glucose level, which helps explain why a glucose test is reliable for this purpose. In contrast, pH, specific gravity, or chloride levels are not reliable indicators for identifying CSF leaks, as they can vary and don’t uniquely differentiate CSF from other fluids.