I worry at the relationship usually assumed between hyperkalaemia and
haemolysis. The two are undoubtedly related, but not as simply as might be
understood from the correspondence, and by those who try and 'correct'
values on the basis of a haemolysis index.
Potassium leakage from the cells may be as a result of failure of cell
membrane integrity or of the haemostatic mechanism in the membrane as in an
old sample.
Thus one can have any combination of :
1. old sample which will exhibit hyperkalaemia but no visible 'haemolysis'
(membranes intact but non functioning) and
2. damaged sample with visible 'haemolysis' but totally unknown level of
redress of the released potassium by the remaining intact and functional
membranes.
with best wishes
Richard
Richard Mainwaring-Burton
Consultant Biochemist
Queen Mary's Hospital
Sidcup, Kent
DA14 6LT
020-8308-3084
-----Original Message-----
From: Jeff Seneviratne [mailto:[log in to unmask]]
Sent: 05 May 2005 15:17
To: [log in to unmask]
Subject: Re: PSEUDOHYPERKALAEMIA?
We should comment as (lab) contributors to Ismail's article in the
BMJ.
It is exactly because of our concern about pseudohyperkalaemia that we
have a policy of not reporting potassium in the presence of haemolysis,
which is, as you say, most likely to have occurred in vitro. However,
in the case presented, the clinical team believed that a potassium
result would have been helpful to their management, since the patient
had in vivo haemolysis. The point is that in such circumstances there
needs to be good liaison between the laboratory and clinicians. There
is also a need to be aware that in vivo haemolysis does not rule out
concurrent in vitro haemolysis, which will give an additional unknown
elevation of potassium.
Jeff Seneviratne
Gill Burrows
>>> Peter Stromberg <[log in to unmask]> 04/05/2005
09:28:14 >>>
Having lost interest in the film my wife was watching I read the paper
by Ismail et al in the BMJ ( 23/4/05,VOL 330 PAGE 949 ) which disturbed
me a bit having recently given two tutorials on hyperkalaemia.It is my
view , particularly with the advent of phlebotomy, artifactually raised
Potassium is much more common these days whether it be due to poor
venepuncture technique or some form of cross-contamination from FBC
tubes. Atrifactually raised Potassium must be much commoner than in-vivo
haemolysis or am I missing cases? What are the causes of in-vivo
haemolyses and how do we identify them? I dont believe we will do
clinicians any favours by issuing all Potassium results from haemlysed
samples. How do our listeners handle this situation.
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