Blood Sciences Test


Spectrophotometric scan for xanthochromia in CSF

Reference:

Cruickshank A et al. Revised National Guidelines for the analysis of cerebrospinal fluid in suspected subarachnoid haemorrhage. Annals of Clinical Biochemistry 2008; 45: 238-244.

Spectrophotometry is much more sensitive than the naked eye in detecting xanthochromia. Xanthochromia typically will not appear until 2-4 hours after the ictus. In nearly 100% of patients with an SAH, xanthochromia is present 12 hours after the bleed and remains for approximately 2 weeks. Xanthochromia is present 3 weeks after the bleed in 70% of patients, and it is still detectable at 4 weeks in 40% of patients.

Specimen guidelines for requestors:

CT scan should have been requested (only proceed with CSF spectrophotometry in the case of negative and equivocal CT scans)

  1. The LP should be delayed for at least 12 hrs following onset of symptoms. We need to record this information on the request form.
  2. Wherever possible collect four sequential CSF specimens (tube 1 fluoride, tubes 2 & 3 microbiology, tube 4 to chemistry)
  3. The CSF specimen for spectrophotometry will require a minimum volume of 900 uL – ideally 1 ml (This equates to approx. 24 drops from the Luer connector on the needle).
  4. Sample should be collected into a 28 ml sterile universal container                                            *NOTE : A CSF sample collected into a serum tube must NEVER be used for Xanthochromia analysis.*
  5. The specimen should be protected from light (Brown Envelope)
  6. Make sure the specimens are sent to the laboratory promptly but DO NOT send samples to the laboratory using the pneumatic tube system.
  7. A serum specimen should be collected at the same time for bilirubin and total protein estimation.

Sample types :

Other information : The CSF absorbance at 476 nm and the CSF protein will be reported.

Reference Range

Results Interpretation
CSF absorbance at 476 nm is < or = 0.007 Not consistent with SAH
CSF absorbance at 476 nm is >0.007 and CSF protein is normal Consistent with SAH or other source of CSF blood
CSF absorbance at 476 nm is >0.007 and CSF protein is elevated Consistent with SAH, other source of CSF blood, or increased bilirubin accompanying increased CSF protein – interpret results with caution.

 Turnaround time

1 day

Availability

Local test

Cannot be added on to an existing request

Specimen Labelling Procedure