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Hi All, Does anyone use calcium loading test to differentiate absorptive from renal wasting hypercalciuria in patients with renal stones? Do you find it necessary to do it? Does it affect the way you manage these patients? If anyone is using this protocol, I would be very grateful if you can email it to me Thank you Soha Zouwail SpR Chemical Pathology Poole Hospital ________________________________ From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Stoddart, Heather Sent: 11 November 2008 10:38 To: [log in to unmask] Subject: tTG & IgA Dear all, Many thanks to all those who responded to my previous query regarding follow on testing when an abnormal IgA is discovered on coeliac screening. I have anonymised all responses, and they are below. Following some audit work, we have adopted a policy of reflexing IgG & IgM and electrophoresis on all samples with IgA <0.1 or >8 g/L, and notifying the requesting clinician and requesting a further sample if immunofixation is required. Heather Heather Stoddart Senior Clinical Scientist Chemical Pathology, St Mary's Hospital Imperial College Healthcare NHS Trust Praed St, London, W2 1NY tel: 020 7886 1355 / 1268 fax: 020 7886 1904 email: [log in to unmask] This has been passed on to me for comment. At the *** Hospital IgA screening is done on all sera which have an OD below 1 as this identifies low IgA samples. If there is an IgA of less than 0.07 g/L by nephelometric assay we do an Ochterlony assay. If there is no IgA to be seen, and IgG Endomysial antibody test is carried out for Coeliac testing and the IgA reported as deficient for the requesting clinican to be aware of possible problems related to IgA deficiency. If the IgA is raised to above normal this could indicate infection or inflammation (often mucosal) and there is a possiblity of liver disease or gammopathy. The decision to do any more tests is based on available clinical and diagnostic test information and left to the Clinical Immunologist authorising tests. It is NOT routine to test for all the immunoglobulins. Patients with pathological IgA increases will inevitably be identified and diagnosed by symptoms which indicate that they require the appropriate tests to be done! We currently analyse IgG tTG alongside IgA tTG as a logistically easier way (and cost effective) of providing relevant supportive diagnostic information. Our analyser also gives us good information as to likely IgA deficient patients (error on IgA tTG result) and these samples we run immunoglobulin measurements on (same combined analytical lab with autoimmune work incorporated with the biochem section of pathology - no separate "immunology" section). In *** Hospital we perform around 400 anti-tTG assays a week. We do not test IgA on all of them. If requested to test IgA we do, if the assay OD is low we do, and we specifically look at all paediatric requests and decide whether IgA testing is indicated. Incidentally we've detected positive anti-tTG abs down to levels of 0.3 g/L IgA measured on the Behring nephelometer. Whether the IgA is high or low we also go on to measure IgG and IgM. I would perform serum electrophoresis where immunoglobulin levels are abnormal in adults over 30 years old (although this suggested age is not from a specific policy). Clearly it's not always appropriate to do SEP on all abnormals, it depends on the situation e.g. all immunoglobulins raised in a patient with liver disease is unlikely to be anything other than polyclonal. It depends on the pattern and clinical situation. If you wanted to keep things simple/quicker you would have to do SEP and full Igs as soon as a low/high IgA is detected. As to the appropriateness, we've identified multiple paraproteins in people being investigated for coeliac disease because of anaemia and have never received a complaint when more information is generated than was asked for. We measure tTG on a DiaSorin Liaison (in biochemistry) as a response to request for 'coeliac screen'. All tTG results carry the message : Patients with IgA deficiency may give falsely LOW tTG results. IgA levels should be checked if there is any clinical suspicion of IgA deficiency. There is a limit to how many hands we can hold. I would expect the clinician to call the shots if there is a strong suspicion of celiac and normal tTG. In *** Hospital, our protocol for coeliac screening has always included detection of both IgA and IgG antibodies on all patients. IgA deficient individuals with untreated coeliac disease will produce IgG antibodies. Discussion with our consultant gastroenterologists has shown the need for confidence in the negative results and the ability to diagnose coeliac disease in IgA deficient individuals. In April 2007 we changed from IgA and IgG endomysial antibodies to IgA and IgG TTG antibodies (Phadia Immunocap). The positives and equivocals are confirmed by IgA and IgG endomysial antibodies and patients with only IgG antibodies also have IgA measured (immunoglobulins and electrophoresis investigations are done in immunology here). Since April 2007 we have found at least 6 patients with IgA deficiency and coeliac disease who would otherwise have remained undetected if we only tested for IgA TTG antibodies. We issue an interpretive comment "These results are suggestive of coeliac disease in an individual with IgA deficiency" IMPERIAL COLLEGE HEALTHCARE NHS TRUST NOTICE: This message may contain confidential information and is intended only for the individual named. 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