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Electronic Letters to:
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Electronic letters published:
![[Read eLetter]](/icons/misc/sectionDOWN.gif){kind=icon}
Confusion over fatty acids
Re: Confusion over fatty acids
Concerning the better performance of H-FABP in the early detection of AMI.
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Keith N Frayn, Clinical Scientist University of Oxford
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keith.frayn{at}oxlip.ox.ac.uk Keith N Frayn
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Dear Editor Azzazy and colleagues make an interesting case for the measurement of “unbound free fatty acids” (FFAu) and heart-type fatty acid-binding protein as diagnostic markers (1). But in their review of FFAu they perpetuate confusion about this term. They discuss data from the Paris Prospective Study showing that elevated fatty acid concentrations predict sudden death (2). However, the measurement in that study was not of FFAu, it was of total plasma FFA concentration. There is great potential for confusion between unbound fatty acids, which, as Azzazy and colleagues point out, may be referred to in the literature as the “free fraction”, and free fatty acids. This is one reason that many European authors prefer the term non-esterified fatty acids to the term free fatty acids, which is prevalent in the North American literature. Non-esterified fatty acids seem prone to confusion: the journal Diabetes still gives the ‘conventional unit’ for their concentration as “mg/ml” but the SI unit as “g/l”, when of course they are usually measured directly in molar terms. References 1. Azzazy HME, Pelsers MMAL, Christenson RH. Unbound free fatty acids
and heart-type fatty acid-binding protein: diagnostic assays and clinical
applications. Clin Chem 2006;52:19-29. Keith N Frayn, PhD |
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Hassan M. E. Azzazy, Associate Professor The American University In Cairo, Maurice M. A. L. Pelsers, Robert H. Christenson
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hazzazy{at}aucegypt.edu Hassan M. E. Azzazy, et al.
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We are grateful to Dr. Frayn for bringing this issue to the readers attention. Although we mentioned in the text of our review that the Paris Prospective Study measured plasma FFA (not FFAu), we regret that there was an error in Table 2 where the acronym "FFAu" was used in place of "FFA" to refer to the findings of the Paris study. |
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Jaimie Breugelmans, Pharm. Antwerp University Hospital, Clinical Biology
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jaimie.breugelmans{at}student.ua.ac.be Jaimie Breugelmans
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Dear Editor, Hassan Azzazy’s reasoning, explaining the observed higher sensitivity of H-FABP to myoglobine in the early detection of AMI, incorrectly states that this may be related to the higher cardiac tissue content of H-FABP compared to myoglobin and that this, in addition to the far lower reference values for H-FABP in plasma, contributes to the more rapid increase of H-FABP above the upper reference limit (URL). However, the proper train of thought should be that despite the 5-fold lower concentration of H-FABP compared to myoglobin in cardiac tissue, this characteristic is fully compensated by the 10 to 15-fold lower decision limit, resulting in a more rapid increase of H-FABP above the URL compared to myoglobin (1,2). The 10 to 15-fold lower decision limit is due to the higher myocardial specificity of H-FABP, which results in a lower aspecific, continuous release from damaged skeletal muscle. References 1. Glatz JFC et al. Fatty acid-binding protein and the early detection of acute myocardial infarction. Clin Chim Acta 1998;272:87-92 2. Alhadi HA, Fox KAA. Do we need additional markers of myocyte necrosis: the potential value of heart fatty-acid-binding protein. Q J Med 2004;97:187-198 |
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