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Hassan Afaf asked if Elizabeth's disappearing false positive TnT could be due to an interfering antibody, e.g., rheumatoid factor (or heterophile Ab, HAMA, etc.). These could certainly cause a false positive, but the FP result should be reproducible on the same sample and usually about the same degree of interference in sequential samples for a period of time (maybe even for a long time). -Jim >>> Hassan Afaf <[log in to unmask]> 11/3/2006 9:32 AM >>> Dear james could this particulate matter you mentioned be IgG especially because this patent has rheumatiod arthritis with a high posiibility of increased level of circulating immunoglobulins afaf -----Original Message----- From: Clinical biochemistry discussion list To: [log in to unmask] Sent: 25/10/06 18:26 Subject: Re: False high Trop T Elizabeth asked about why a micro-clot (or similar) would cause a false high on the Elecsys TnT (or any TnI for that matter). As I mentioned in my reply, which I inadvertently sent to you instead of the list, we see an occasional false elevation of TnT that "disappears" when repeated and presumed to be due to micro-clots. The only evidence of that is that they are less frequent with centrifugation immediately before assay. (We use heparin plasma.) One possible mechanism is TnT (or its various complexes) sticking to particulate matter and being somewhat concentration in the reaction mixture. Another possibility is for the particulate matter to cause some degree of "sandwiching" of the capture and detection antibodies. I look forward to others' ideas. As I mentioned, there may also be false negatives, perhaps more common, due to short sample that we just don't suspect because < 0.01 ng/mL is the most common result. -Jim ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk ( http://www.acb.org.uk/ ) List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/ DISCLAIMER: This e-mail and any attached files are confidential and may also be legally privileged. They are intended solely for the intended addressee. If you are not the addressee please e-mail it back to the sender and then immediately and permanently delete it. Do not read, print, re-transmit, store or act in reliance on it. This e-mail may be monitored by Salford Royal NHS Foundation Trust in accordance with current regulations.. This footnote also confirms that this e-mail message has been swept for the presence of computer viruses currently known to the Trust, however the recipient is responsible for virus-checking before opening messages and attachments. Unless otherwise stated, any views expressed in this message are those of the individual sender and may not necessarily reflect the views of Salford Royal NHS Foundation Trust. As a public body, the Trust may be required to disclose this email and/or any response under the Freedom of Information Act 2000 unless the information in the email and/or any response is covered by one of the exemptions in the Act. ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk ( http://www.acb.org.uk/ ) List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/ ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/