CSF Xanthochromia for suspected subarachnoid haemorrhage

Blood Sciences Test

---

CSF Xanthochromia for suspected subarachnoid haemorrhage

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:

A CT scan should have been performed (only proceed with CSF spectrophotometry in the case of negative/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 4 sequential CSF specimens (tube 1 fluoride oxalate, tubes 2 & 3 microbiology, tube 4 plain universal to chemistry)
3. The CSF specimen for spectrophotometry will require a minimum volume of 900 uL – ideally 1 ml
4. Sample should be collected into a 25 ml sterile universal container                                                                                                                                     NOTE : A CSF sample collected into a serum tube CANNOT 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 paired serum specimen should be collected at the same time for bilirubin and total protein estimation.

Sample types :

• CSF – the 4th sample to be withdrawn into a plain universal tube and should be sent promptly to the lab, protected from light, and use of the pneumatic tube (POD) system must be avoided. A minimum sample volume of 900 uL is required.
• A paired clotted blood for protein and bilirubin – the CSF result will be corrected if the serum bilirubin is greater than 20 µmol/L

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

Interference:

Oxyhaemoglobin is a cause of interference, if the concentration is too high then there is a danger that this could mask any bilirubin present in the CSF specimen.

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.

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.

Turnaround time

1 day

Availability

Local test

Cannot be added on to an existing request

Specimen Labelling Procedure