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PTD - 217

Test Directory - CSF spectrophotometry

A protocol for collection, handling and transport of CSF requiring spectrophotometry for detection of bilirubin (xanthochromia) is available (pdf format).

Synonyms

CSF xanthochromia

Clinical Indications

The test is performed to try and identify patients who have had a subarachnoid haemorrhage (SAH) but in whom the CT scan is negative. After SAH, haemolysis of subarachnoid erythrocytes releases haemoglobin, which is converted to bilirubin. Bilirubin concentration reaches a maximum at about 48 hours and may last for 2 to 4 weeks after extensive bleeding. Because the formation of bilirubin after haemorrhage is a time-dependent process, CSF must be sampled at least 12 hours after a suspected event.

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

On request.

Specific Criteria

The following must be indicated on the request form:
 - Clinical indication for request
 - Result of CT scan
 - Time of onset of symptoms/event
 - Time of lumbar puncture
 - If the differential diagnosis includes meningitis

Patient Preparation

CSF must be sampled at least 12 hours after a suspected event.

Turnaround Time

Within 24 hours

Specimen

CSF collected sequentially (the first few ml. of fluid should not be used for this investigation). The first fraction should be collected into a grey top fluoride tube for glucose. CSF may also be required for microbiology and should be collected next (2nd and 3rd  fractions into 2 white capped universals). The specimen for spectrophotometry should be the last fraction (4th) fraction taken. A blood sample (yellow top SST) should be taken at the same time for bilirubin, total protein and glucose.
N.B. If only 3 CSF fractions can be collected then the last sample should be sent according to suspected diagnosis i.e. ?infection / meningitis send to Microbiology, if ?SAH send to Biochemistry.

Volume

Minimum of 1 ml.

Container


White Capped Universal

Sample should be protected from light and transported to Clinical
Biochemistry immediately.
Do not use the pneumatic tube system.

Causes for Rejection

CSF sample taken less than 12 hours after suspected event.
Insufficient information regarding timing of sample.

Delay in sample reaching laboratory

Interpretation

The report will consist of an interpretation:

Not consistent with SAH (low CSF bilirubin relative to serum)

Consistent with SAH or other source of CSF blood (increased CSF bilirubin relative to serum with normal CSF protein)

Consistent with SAH, other source of CSF blood or increased bilirubin accompanying increased CSF protein - interpret results with caution (increased CSF bilirubin relative to serum with increased CSF protein)

Lab. Handling

Processing: CSPEC and Centrifuge CSF sample as soon as possible after receipt and within 1 hour of collection. Store supernatant in the dark at 4C in separating fridge (CB39) until analysis.
(NOCSF & save)

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Version 1.1 / July 2015                                                                                                          Approved by: Consultant Biochemist