We wish to add a cautionary note regarding removal of the correction for serum bilirubin in the presence of increased cerebrospinal fluid (CSF) bilirubin and oxyhaemoglobin from the revised national guidelines for the analysis of CSF for bilirubin in suspected subarachnoid haemorrhage (SAH).1

Recently we received a CSF sample requesting “xanthochromia” from a patient who had a normal CT brain scan. On CSF spectroscopy, both oxyhaemoglobin and bilirubin peaks were clearly visible. The net oxyhaemoglobin (OxyHb) and bilirubin absorbance were 0.0205 AU and 0.0146 AU, respectively. Under the revised guidelines1 this would have been unequivocally but erroneously reported as “Bilirubin and oxyhaemoglobin increased. …