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We check all positive TTG with EMA. About 2% of our requests are positive so this amounts to a slide a week. This would be no different if we just confirmed 'weakly positive' results. Difficult to define 'weakly positive' but I use <30 u/mL (double the lower limit of the ref. interval, which is <15 u/mL). We use Biorad Bioplex 2200 TTG-IgA/G assays. Best Wishes Steve Steve Holding PhD FRCPath Consultant Clinical Scientist (Clinical Immunology) Honorary Professor, Hull York Medical School Blood Sciences, Pathology Dept, Hull and East Yorkshire Hospitals, Anlaby Road, Hull, HU3 2JZ o +44 (0)1482 607710 -----Original Message----- From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of CLIFFORD-MOBLEY, Oliver (UNIVERSITY HOSPITALS BRISTOL NHS FOUNDATION TRUST) Sent: 15 June 2018 17:21 To: [log in to unmask] Subject: Coeliac serology Dear mailbase, NICE NG20 recommends confirming weakly positive IgA TTG antibodies with IgA endomysial antibodies (EMA). How have other centres defined and verified the TTG weakly positive range? We recently switched TTG assay and during our verification found that some TTG results above the manufacturer's stated weakly positive range were negative by EMA. Therefore we are currently confirming all positive TTG by EMA and not defining a 'weakly positive' range - are any other centres doing the same thing? The alternative we could consider is to define the upper limit of the TTG weakly positive range such that it has 100% concordance with EMA positivity. However the question that arises from this is whether EMA should be considered the gold standard: I understand that it has a greater specificity than TTG for CD but I also believe that a false negative EMA is still possible. Many thanks, Oliver Clifford-Mobley FRCPath Principal Clinical Scientist Department of Clinical Biochemistry University Hospitals Bristol NHS Foundation Trust T: 0117 342 7833 ******************************************************************************************************************** This message may contain confidential information. If you are not the intended recipient please inform the sender that you have received the message in error before deleting it. Please do not disclose, copy or distribute information in this e-mail or take any action in relation to its contents. To do so is strictly prohibited and may be unlawful. Thank you for your co-operation. NHSmail is the secure email and directory service available for all NHS staff in England and Scotland. NHSmail is approved for exchanging patient data and other sensitive information with NHSmail and other accredited email services. For more information and to find out how you can switch, https://portal.nhs.net/help/joiningnhsmail ------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 Green Laboratories Work http://www.laboratorymedicine.nhs.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 Green Laboratories Work http://www.laboratorymedicine.nhs.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/