Chemical Pathology


NB; This test is rarely required as in general adds no additional information to the usual Microbiology investigations.

  • Cerebral spinal fluid (CSF) lactate concentrations normally parallel blood levels, but in cases of biochemical alteration in CNS, CSF lactate may change independently of blood levels.
  • Raised levels of CSF lactate may occur with severe cerebral hypoxia or genetic lactic acidosis, intracranial haemorrhage, bacterial meningitis and epilepsy.
  • CSF lactate concentrations greater than 4.0 mmol/l are strongly predictive of bacterial meningitis, with a sensitivity of 88% and specificity of 98%. An increased CSF lactate is found earlier than a reduced glucose in bacterial infection.
  • In viral meningitis, lactate levels remain normal, even when neutrophils are present in the CSF.

Sample requirements

A minimum of 0.25mL CSF (preferably tap #2 or #4) taken into a fluoride-oxalate tube sent immediately to the laboratory.

0.25ml CSF fluoride-oxalate tube

  • Please note: 1 mL of CSF is approximately equal to 25 drops from the Luer connector of the needle
  • Samples from CGH are sent directly to GRH Pathology from the ward or from CGH Pathology if delivered there.
  • If other CSF investigations are required please check the CSF Sample requirements webpage for further details

Required information

Relevant clinical details. State tap number and date and time of lumbar puncture on samples along with required patient identification details.

Turnaround times

Samples are normally analysed within one hour of receipt in the assaying laboratory. The test can be ordered urgently.

Reference ranges

The adult reference range for CSF lactate is 1.1 – 2.4 mmol/L.

For diagnostic purposes, the results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Further information

To learn more about CSF analysis, visit Lab Tests Online.

Page last updated 05/08/2016