Cerebrospinal fluid for glucose assay should be

• A. refrigerated
• B. analyzed immediately
• C. heated to 56C
• D. stored at room temperature after centrifugation

Answer: (B)

Glucose in cerebrospinal fluid can continue to be consumed by cells present in the sample after collection. If there’s any delay, glycolysis lowers the measured glucose value, giving a falsely low result. Analyzing the sample immediately prevents this artifactual change and yields the value that reflects the patient’s true CSF glucose at collection. Refrigeration slows glycolysis but does not stop it completely, so a delayed test can still be inaccurate; heating would alter components in undesirable ways, and storing at room temperature after processing allows glycolysis to continue as well. Therefore, the best practice is to analyze the CSF glucose assay immediately.