Graham, That sounds much more reasonable, I had hoped I had missed something. Just out of interest, do you notice the effect of renal dialysis clinics in the reports? assuming that you have clinics run on set days? I recall trying to monitor creatinine by AoN and, interestingly, the effect of pre-dialysis high creatinine was never really an issue as they would be removed by the algorithm as being outside the truncation limits. The issue was the ULN and moderately high post-dialysis creatinines which would shift the AoN out erronously. I also suspected the same issue with over-dialysed low potassium results. Best regards, Andy Minett Specialist Biomedical Scientist Biochemistry Pathology Hull Royal Infirmary ------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/