Bilirubin, ferritin, D-dimers anderythrophages in thecerebrospinal fluid ofpatients withsuspected subarachnoid haemorrhage butnegative computed tomography scans

Aim-To assessthediagnostic valueof cerebrospinal fluid(CSF)spectrophotometry, cytology, ferritin, andD-dimer measurements intheinvestigation ofsuspectedsubarachnoid haemorrhage in patients withnegative orequivocal computedtomography (CT)scans. Methods-CSFspecimens submitted for assessmentof xanthochromia were examinedforerythrophages usinga cytospinpreparation stainedwith Wright's stain, forferritin usingthe Ciba-Corning MagicIRMA assay,Ddimersusing theDimertest 2latex agglutination slide test, andforbilirubin by scanningspectrophotometry. The patients weredivided intothreegroups fordataanalysis andtheresults comparedwiththeexisting methods, CT,and angiogram results. Finaldiagnoses were reviewed byaconsultant neurologist. Results-Thirty sixpatients wererecruited. Inthosepatients withconfirmed subarachnoid haemorrhage CSF cytology hadalowsensitivity andthere werefalse negative results withboththeD-dimer andferritin assays. Eleven patients witha negative orequivocal CT scanunderwent angiography, butonlyoneaneurysmand no arterio-venous malformations or bleeding points wereidentified. Inthe patient withtheaneurysmtherewasno laboratory evidenceof subarachnoid haemorrhage. Sixpatients had CSF abnormalities detected by thespecial testsonlyandinnoneofthesecaseswas subarachnoid haemorrhage confirmed. Allresults werenormalinfouroutoffive casesoftraumatic tap. Conclusions-This isasmallstudy, butit showsthat, depending onthetiming of the lumbar puncture,falsenegative results canoccurwithbothferritin and D-dimermeasurements. Itsuggests that neither ofthesetests addssignificantly to theinformation provided byCT,visualisationofCSF,and spectrophotometry and confirms that,despite theuseof spectrophotometry,