Laboratory: Clinical Biochemistry  (METABOLIC)
Test Name:
Test Code: SFXA
Clinical Information:
Subarachnoid haemorrhage (SAH) is spontaneous arterial bleeding into the subarachnoid space, usually from a cerebral aneurism. The initial investigation, the demonstration of blood on a computed tomography (CT) scan, is positive for blood in 98% of patients with a SAH presenting within the first 12 hours after an event. CT positivity drops to about 50% in patients presenting after one week. Xanthochromia testing is required for assessment of patients presenting with a history suggestive of SAH and negative CT findings.

Cruikshank A, Auld P Revised National Guidelines for Analysis of Cerebrospinal Fluid for Bilirubin in Suspected Subarachnoid Haemorrhage. Ann Clin Biochem 2008; 45: 238-244
Beetham R. National Guidelines for Analysis of Cerebrospinal Fluid for Bilirubin in Suspected Subarachnoid Haemorrhage. UK National External Quality Assessment Scheme for Immunochemistry Working Group. Ann Clin Biochem 2003; 40: 481-488
Goyale A, O’Shea J et. al. Analysis of Cerebrospinal Fluid for Xanthochromia versus Modern Computed Tomography Scanners in the Diagnosis of Subarachnoid Haemorrhage: Experience at a Tertiary Trauma Referral Centre. Ann Clin Biochem 2016, 53(1): 150-154

CSF should not be collected until at least 12 hours after the onset of symptoms and only if the CT scan is not positive for blood.
The test should be performed on the final CSF specimen collected.
If last tube is not available, indicate which tube the sample is and send to the HSC Biochemical Genetics lab. The testing site will assess sample suitability.
A plasma sample should be collected simultaneously for bilirubin and total protein testing to assist with interpretation.
Collection Devices:
Specimen Required:
Cerebrospinal Fluid: 1.0 mL
Pediatric Cerebrospinal Fluid: 1.0 mL

Protect the specimen from light during transport (plastic specimen bag inside brown envelope or wrapped in foil).
Stability 1 day at room temperature, 7 days refrigerated. Do not freeze.

Protect specimen from light. Store and ship refrigerated if analysis will not be performed within 24 hours.
Reference Values:
< 0.008 absorbance units
An interpretation is included in the report.
0800h - 1600h
See Also:
More Information: