Specimen Collection
1 mL CSFLumbar puncture: Collect 4 tubes
- the first 3 are for routine microbiology
- the 4th tube is for bilirubin; the sample should be a minimum of 1 mL and light-protected.
Sample must be protected from light - wrap sample in tin foil.
Visual inspection for xanthochromia will be performed on all CSF samples in the Microbiology laboratory.
Spectrophotometry will be performed on all samples when "xanthochromia" is specifically requested, or when "? subarachnoid haemorrhage" is stated as clinical information on the request form.
If the patient has had recent neurosurgery please write "recent neurosurgery" on the form to avoid this test being performed unnecessarily.
Reference Intervals
Normal CSF Bilirubin
: 0 - 7 mAU (milli-absorbance units)
Uncertainty of Measurement
: 16%
Turnaround Time: Within 3 hours
Diagnostic Use and Interpretation
Xanthochromia is the term used for cerebrospinal fluid (CSF) stained yellow with bilirubin. This is the result of a recent subarachnoid or cerebral bleed, head injury, or previous bloody tap. Bilirubin is formed ONLY in vivo, and not after CSF has been taken. Xanthochromia may take up to 12 hours to develop following a bleed; a false negative result is possible if CSF is obtained earlier than this.
Oxyhaemoglobin is found in BOTH subarachnoid haemorrhage and bloody taps.
CT scanning has a high sensitivity (97%) for detecting subarachnoid haemorrhage. Xanthochromia testing should be performed in patients with a clinical history suggesting SAH who are CT scan negative.
The CSF may contain bilirubin for up to several weeks while blood is visible on CT scan for several days only. For a patient who had a severe headache several days ago, but where no blood is visible on CT scan, the detection of xanthochromia might be useful.
Passive transfer of bilirubin from the plasma may cause a positive xanthochromia test in patients with jaundice, and is not uncommon in normal neonates. It may also occur when there is a high CSF protein concentration (> 1500 mg/L e.g. Froin's syndrome) or when the CSF is heavily contaminated with plasma as in a significantly bloody tap. A yellow coloured CSF may also be seen due to rifampicin therapy or carotenaemia.
If the serum bilirubin and total protein levels are known, a calculation will be done to determine whether the observed level of CSF bilirubin is accounted for by passive transfer from plasma. For this reason a serum/plasma sample from the patient (taken on the same day if possible) is required.
Haemolysis starts to occur 2 hours after red blood cells enter the CSF, giving rise to a pink colour due to oxyhaemoglobin. Spectrophotometry of CSF permits identification of both oxyhaemoglobin and bilirubin when present in CSF.
References:
1. Cruickshank AM. CSF spectrophotometry in the diagnosis of SAH. J Clin Pathol 54:827-30, 2001.
2. Edlow JA and Caplan LR. Primary care: avoiding the pitfalls in the diagnosis of SAH. N Eng J Med 342(1):29-36,2000.
3. Shah KH et al. Distinguishing traumatic lumbar puncture from true SAH. J Emerg Med 23(1):67-74,2002.
4. UKNEQAS. National guidelines for the analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage. Ann Clin Biochem 40: 481-8, 2003.
Contact Information
For further information, contact the Microbiology Department via Lablink or the Clinical Microbiologist:
Lablink contact details
Dr Sally Roberts
, Microbiologist:
ext 22705
Cellphone
021 674 140
Dr Sharmini Muttaiyah
, Microbiologist:
ext 22700
Cellphone
021 615 892
Dr Mary de Almeida
, Microbiologist:
ext 22700
Cellphone
021 170 9117
Dr Matthew Blakiston
, Microbiologist: contact via Lablink
Emails to
chemicalpathologist@adhb.govt.nz
will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via
Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours
: contact
Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad
(Clinical Lead)
:
SamarinaM@adhb.govt.nz
ext. 22402
Dr Cam Kyle:
CampbellK@adhb.govt.nz
ext 22052
Dr Weldon Chiu:
WeldonC@adhb.govt.nz
ext. 23427
Dr Campbell Heron:
CHeron@adhb.govt.nz
ext. 23427
Specimen Transport Instructions for Referring Laboratories
Please send samples to LabPlus at 4C and covered in foil to protect from light. Last aliquot collected to be sent for this analysis. Centrifuge sample within one hour and send supernatant for analysis.