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Dear Peadar, Another possibility, may be familial pseudohyperkalaemia. I have seen a couple of patients who leak potassium more rapidly than normal from their cells in serum or plasma samples at normal ambient temperature. In one, comparing K levels in samples centrifuged at one hour intervals after being taken, with my own taken at the same time at our laboratory, the patient's K increased by approx 1.5 mmol/L at 6 hrs, whereas my K increased by only approx 0.2 to 0.3 mmol/L. ( I am working from memory from some years ago.) This phenomenon was first described, I believe, by Stewart et al. See Stewart, G. W.; Corrall, R. J. M.; Fyffe, J. A.; Stockdill, G.; Strong, J. A. : Familial pseudohyperkalaemia: a new syndrome. Lancet II: 175-177, 1979. and OMIM data at http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=177720 Best wishes, Keith. Keith Wakelin Consultant Chemical Pathologist, Dorset County Hospital, Dorchester, Dorset. ----- Original Message ----- From: "Mainwaring-Burton Richard (RGZ)" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, January 11, 2008 3:44 PM Subject: Re: query spurious high potassium We too have seen this with 'fragile white cells' or 'leaky platelets'. Also always check haematology results for raised platelet count, since normal platelets contain significant amounts of potassium, and are all smashed up in clotting. We have had some success with the use of a heparinised sample in both scenarios. with best wishes Richard Richard Mainwaring-Burton Consultant Biochemist Queen Mary's Hospital Sidcup, Kent 020-8308-3084 -----Original Message----- From: gordon challand [mailto:[log in to unmask]] Sent: 11 January 2008 14:38 To: [log in to unmask] Subject: Re: query spurious high potassium Dear Peadar I've seen similar cases which have usually involved refrigeration or potassium/ EDTA contamination; and also an occasional 'leaky high platelets' case. However in view of the information from the GP, one thing I've been concerned about is that I've noticed that many supermarkets now sell 'low sodium salt' - this is potassium chloride rather than sodium chloride. Best wishes Gordon Challand ----- Original Message ----- From: "Peadar McGing" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, January 11, 2008 1:25 PM Subject: query spurious high potassium Dear colleagues, I know this is a topic aired many times and I've written about it myself but I am currently dealing with a case that doesn't quite fit the bill and I wonder if anyone can offer some advice. The case is of a woman in her 50s who had blood taken by her GP and sent via the normal courier system to the lab. Patient was asymptomatic. Sample was sent in on the 8th and repeated on the 9th. Because of the high K which was phoned by the lab, the GP sent her in to AE which she attended the next day (10th). Date Na K Cl TCO2 Urea Creat A.G. 8-1-08 (GP) 151 5.1 107 28 4.2 74 21 9-1-08 (GP) 150 6.6 109 34 3.7 79 14 10-1-08(AE) 138 3.8 102 27 3.3 61 13 ref ranges: Na (133-145), K(3.5-5.0). Units mmol/L except creat (µmol/L) GP said patient is on a lot of medications, including anti-depressants, but the most notable 'medication' was that she was described as 'taking food with her rather salt than taking salt with her food'. We can't rule out refrigeration but we believe it unlikely as a cause in this case. We have some idea but things don't add up fully and I'd appreciate your thoughts, especially if you've seen this scenario before. best wishes. Peadar Dr Peadar McGing, MRCPath EurClinChem, Principal Biochemist, Biochemistry Dept., Mater Misericordiae University Hospital, Eccles Street, Dublin 7, Ireland. Tel: (+353 1)8032080; Fax: (+353 1)8034781. ----------------------------Disclaimer-------------------------------------- This e-mail and any files transmitted with it contain information which may be confidential and which may also be privileged and is intended solely for the use of the individual or entity to which it is addressed. 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