Multi-wavelength spectrophotometric analysis for detection of xanthochromia in cerebrospinal fluid and accuracy for the diagnosis of subarachnoid hemorrhage.
BACKGROUND
Cerebrospinal fluid (CSF) was examined for bilirubin, an important indicator for diagnosis of subarachnoid hemorrhage (SAH).


METHODS
A multi-wavelength (340, 415, and 460 nm) spectrophotometric assay was developed for the quantitative measurement of bilirubin in CSF, enabling the mathematical correction for absorbance of hemoglobin and proteins. Bilirubin and hemoglobin results were correlated to HPLC and a standard colorimetric assay, respectively. A subset of samples was sent for an absorbance reading at 450 nm following baseline correction. The multi-wavelength bilirubin assay was validated on 70 patients with confirmed SAH and 70 patients with neurologic symptoms who ruled out for SAH.


RESULTS
The multi-wavelength spectrophometric assay demonstrated no interferences due to proteins (albumin) up to 30 g/l or oxyhemoglobin up to 260 mg/l. The assay limit of detection was 0.2 mg/l, linear to 20 mg/l, and CVs ranged from 1 to 6% at bilirubin concentrations of 0.84 and 2.1mg/l. The spectrophotometric assay correlated to HPLC and the colorimetric assay for bilirubin and hemoglobin, respectively. Results also correlated to the absorbance method (with removal of samples with high hemoglobin and proteins). The area under the ROC curve for diagnosis of SAH was 0.971 and 0.954 for the HPLC and spectrophotometric assay, respectively. At a cutoff of 0.2mg/l, the clinical specificity was 100% for both assays, and the clinical sensitivity was 94.3% and 88.6% for SAH for the HPLC and spectrophotometric asays, respectively.


CONCLUSIONS
The multi-wavelength spectrophotometric assay is an objective alternative to visual inspection, HPLC, and absorbance for CSF bilirubin.
['Smith|Andrew|A|', 'Wu|Alan H B|AH|', 'Lynch|Kara L|KL|', 'Ko|Nerissa|N|', 'Grenache|David G|DG|']
D000328:Adult D000368:Aged D019540:Area Under Curve D001663:Bilirubin D016022:Case-Control Studies D002851:Chromatography, High Pressure Liquid D003124:Colorimetry D005260:Female D006801:Humans D057230:Limit of Detection D008297:Male D008875:Middle Aged D010108:Oxyhemoglobins D012372:ROC Curve D012015:Reference Standards D012709:Serum Albumin D013053:Spectrophotometry D013345:Subarachnoid Hemorrhage
Xanthochromia Cerebrospinal fluid Cerebrospinal fluid subarachnoid hemorrhage CSF Bilirubin SAH HPLC CV ARUP AU AUC-ROC Association of Regional University Pathologists CNS CT S(y|x) SE SFGH STARD San Francisco General Hospital Studies on Diagnostic Accuracy UCSF UK NEQAS United Kingdom National External Quality Assessment Service University of California, San Francisco absorbance unit area under the receiver operating characteristic curve central nervous system cerebrospinal fluid coefficient of variance computer-aided tomography high performance liquid chromatography standard deviation of residuals standard error