tube assay

Melbourne Health Shared Pathology Service
Xanthochromia by Spectroscopy
Spectroscopic analysis of CSF for xanthochromia is undertaken strictly according to the
following guidelines. These guidelines have been established by predominantly British
biochemists in the light of their experience with the assay over recent years and incorporate
the current understanding of the assay and its interpretation.
Requirements and limitations.
Between the onset of symptoms and the performance of the diagnostic
lumbar puncture [LP], 12 hours must elapse.
Only one LP per symptomatic episode is possible.
All possible precautions must be in place to obviate a bloody tap.
As well as the 3 tubes of CSF usually collected at lumbar puncture, at
least 1 ml of CSF must be collected into a fourth tube. This fourth tube
must be totally protected from light at all times.
o The CSF in the fourth tube is used for the spectrophotometric
assessment of xanthochromia.
o The first three tubes required by the Microbiology Department are
processed by them in the standard fashion, including the assay of
protein in the CSF.
The specimens must NOT be delivered by pneumatic tube: only hand
delivered specimens are acceptable.
A 5 ml blood sample must be drawn into Li-heparin at the same time as
the LP; both it and the LP tubes must be delivered to the laboratory at the
same time, by hand.
Only hand held specimens will be accepted; any specimens delivered
by pneumatic tube will be declined.
The request slip must clearly state the time of symptom onset and
the time of lumbar puncture; failure to do so will cause the request to be
Requests to assay xanthochromia in specimens where the stated time
elapse between symptom onset and LP is less than 12 hours will be
CSF samples in which the first tube has >40,000 RBCs/μL (ie >40,000
X106 RBCs/L) cannot be used for the purpose of xanthochromia assay in
the fourth tube.
CSF specimens lacking the accompanying plasma sample will have their
reporting delayed until the required plasma sample is delivered and
Availability and turnaround
Specimens that arrive in the laboratory between 0800 and 1600 h Monday to Friday
usually will be processed the same day.
Specimens received outside those hours will have the RBC count and other Microbiology
work done immediately and the fourth tube of CSF will be spun immediately and will be
retained, at 4o C and strictly protected from light, but will be processed the following
Monday to Friday working day. Samples may be assayed outside routine hours after
consultation with the Chemical Pathologist, or signed authorisation by the Neuro-surgery
Turnaround, in normal working hours, will be in the order of 90 to 120 minutes from arrival
of all specimens in the laboratory to reporting on CIS.
CHBIS-01,16 (30/10/09)
Dr C Chiang: Oct 09
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