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Elevations in creatine due to dietary supplements wouldnt affect the Jaffe method. Since the results were comparable between enzymatic and Jaffe, I dont see this as an option. Thomas On Tue, Jan 29, 2013 at 10:39 AM, Mohammad Al-Jubouri <[log in to unmask] > wrote: > Hi Maria, > > Really taking exogenous creatine is the only plausible explanation here. > > Best regards > > Mohammad > > Dr. M A Al-Jubouri, MB ChB, MSc, FRCP Edin, FRCPath > Consultant Chemical Pathologist > *From:* maria warner <[log in to unmask]> > *To:* [log in to unmask] > *Sent:* Tuesday, January 29, 2013 2:31 PM > *Subject:* Inexplicably elevated Creatinine > > This message is posted on behalf of a colleague. Please address replies to > [log in to unmask] > > Hi all, > > We are hoping someone might have some suggestions about what could be > causing some unexpectedly elevated creatinine results in a patient with > normal renal function. > > > Our patient is a 44yo male who is currently fit and well and on no > medications. He has a past medical history of sarcoidosis which was > previously treated with longterm prednisolone but he has been off steroids > now for over a year. > > He attended his GP in October 2012 with mild lethargy. U&Es were checked > and found a raised Cr of between 254 and 326 (previous baseline 80 to > 110). He was then referred to renal and underwent a renal biopsy and > magnetic resonance renal angiography which were both completely normal. A > repeat Cr was then checked and was found unexpectedly to be much improved > at 104. > > His Cr levels were then checked on multiple samples, including both high > and low Cr levels, on both enzymatic and kinetic Jaffe assays. The results > were all comparable so it was felt that any assay interference was unlikely. > > More formal assessments of his renal function were then requested > including a Cr clearance which was high at 184 ml/min (serum Cr at the time > was 154) and an isotopic GFR which was normal at 94ml/min, both confirming > that his renal function is essentially normal despite these raised Cr > results. A cystatin C was also checked on samples with high Cr levels and > found to be normal. > > He is a very fit gentleman who regularly cycles between 50 and 100 miles a > day. It appears his elevated creatinine levels are related to exercise as > if he abstains from exercise for 3 days his Cr level is normal. After > cycling 50 miles his Cr was 310 and after cycling 100 miles his Cr was 452. > > His diet has been thoroughly assessed and he definitely does not appear to > be taking any creatine containing supplements. > > We are currently hypothesising that he has some sort of creatinine release > from his muscles following extreme exercise. But we have little evidence > to support this as his CK has always been low (between 43 – 53 U/L) even > after exercise and he has no particular muscle symptoms. His CRP is <1 and > an autoimmune/complement screen are all normal. > > On his next set of samples we plan to check AST, LDH and an acyl carnitine > profile. > > Does anyone have any other thoughts/suggestions? > > Regards, > Sara & Maria > ------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.ukGreen 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/ > > -- > Thomas Kampfrath, Ph.D. > Clinical Chemistry Fellow > Pathology and Laboratory Medicine > University of Louisville > Louisville, KY, 40292 > P: 502-392-0490 > C: 614-377-1918 > F: 502-852-7674 > > > > > > > > > > > ------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/