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Johnathan, Significant levels of carotenoids in the CSF is something I have not encountered and I would have thought unlikely in a patient suffering from myxoedema (generally not very lively subjects). Bilirubin has an absorbance max at 455 - 466 nm. I suspect the method you are using has a correction for carotenoids factored into the calculation (see Varley, 6th edition page 721). If you want to rule out carotenaemia you can use the absorbance spectra of the individual carotenoids to identify them and distinguish them from bilirubin (hopefully you have a scanning spec available). Beta-carotene has an absorbance max at 455, but other maxima at 425 and 479 (the exact wavelength depends on the solvent used). Alpha-carotene has an absorbance max at 444, but other maxima at 422 and 474, lycopene has an absorbance max at 472, but other maxima at 444 and 502. etc etc (e-mail me if you want references for all this or sample scans of carotenoids) So if you scan you will have no difficulty distinguishing these and other carotenoids from bilirubin. Nick Miller London On 27 October 2011 13:45, GOMEZ JAVIER (RM1) Norfolk and Norwich University Hospital <[log in to unmask]> wrote: > Carotenes are absorbed at around 460nm (mentioned in Tiezt textbook) but the > effect if probably negligible in most cases – unless on high content diet or > supplements? > > > > · Xanthochromia in the Cerebrospinal Fluid Pract Neurol > 2004;4:174-175 > > > > · Cerebrospinal fluid as a diagnostic body fluid The American > Journal of Medicine Volume 75, Issue 1, Part 2, 28 July 1983, Pages 102-108 > > > > Javier Gomez > > > > > > ________________________________ > > From: Clinical biochemistry discussion list > [mailto:[log in to unmask]] On Behalf Of Vernazza Jonathan > (IMPERIAL COLLEGE HEALTHCARE NHS TRUST) > Sent: 26 October 2011 15:11 > To: [log in to unmask] > Subject: Xanthochromia and carotene > > > > Dear All, > > We have had a query from one of our neurologists regarding a xanthochromia > result, and wondered if anyone might be able to help. The request originated > from a myxoedematous patient (TSH 82 mu/L, previous diagnosis several years > ago of Hashimoto's encephalopathy) who has had xanthochromia requested (due > to sudden onset left frontal headache). > > NBA = 0.015 > NOA = 0.008 > CSF protein = 1.3 g/L > Serum total protein = 76 g/L > Serum bilirubin = 53 umol/L > > If I have followed the algorithm correctly, this leads to the comment: > Increased CSF bilirubin. This finding may be consistent with: SAH; an > increased bilirubin accompanying the increased CSF protein; or other source > of CSF blood. Interpret result with caution in relation to SAH especially if > within first week of event. > > The CT scan is negative, CT Angio negative. The time between onset of > headache and LP is not known. > > The question from the neurologist is: are we aware of false > positive xanthochromia results in myxoedematous patients, possibly due to a > carotenaemia? Or do we just explain this result through the CSF protein. I > believe carotene does absorb across this region, but not sure if it would be > in sufficient quantity to interfere. A quick literature search has not > yielded any recent papers/case reports. > > > > Any help / comments appreciated. > > Many thanks, > Jon > > > > > > Mr. Jonathan Vernazza > > Registered Clinical Scientist > > Clinical Biochemistry Department > > Imperial College Healthcare NHS Trust > > Telephone: 020 331 15181 > > Email: [log in to unmask] > > ******************************************************************************************************************** > > This message may contain confidential information. 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