CSF Bilirubin (Xanthochromia)

Clinical Chemistry

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Description

Subarachnoid haemorrhage ( SAH ) is a spontaneous arterial bleed into the subarachnoid space, usually from an intracranial aneurysm. It is important to detect SAH as early as possible to achieve the best outcome. A head CT scan is performed initially to look for the presence of a bleed. This will be positive in 98% of patients presenting within the first 12 hours after an event. However, sensitivity falls to around 50% in patients presenting after 1 week. Patients with a positive CT usually proceed to cerebral angiography to confirm the presence of an aneurysm and locate its site. This invasive procedure carries with it a small but definite risk of morbidity and mortality. CSF bilirubin ( xanthochromia ) is measured with the aim of detecting the 2-5% of patients who have sustained a recent SAH but are CT negative, the larger proportion who present late, and for eliminating the diagnosis in other cases to avoid a potentially hazardous procedure. Following haemorrhage into the CSF, red blood cells undergo lysis ( haemolysis ) and phagocytosis; the liberated oxyhaemoglobin is converted in-vivo in a time-dependent manner into bilirubin. Only bilirubin arises solely from in-vivo conversion. As haemolysis can be induced in pneumatic tube specimen transport systems, specimens should be delivered to the laboratory by hand.

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Indications

Investigation of sudden-onset headache where subarachnoid haemorrhage is suspected and CT-scan and CSF white cell count is normal.

A serum sample for bilirubin and total protein measurement should be collected at the same time. CSF protein should also be measured because increased bilirubin can accompany
an increased CSF protein

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Sample Type

CSF - 2 ml, 4th sample, protected from light, at more than 12 hours ( and less than 14 days ) after the onset of symptoms. CSF should be delivered to Clinical Chemistry promptly. Do not use the vaccum tube delivery system.

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

1 Working Day (Mon-Fri excluding Bank Holidays)

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Testing Frequency

Weekdays during routine working hours ( generally not available out-of-hours ). Must be in Lab by 2pm for same day analysis.

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.