See also: Bertholf RL, Bertholf MF, Brown CM, Riley WJ. Ionized calcium
buffering in the transfused anhepatic patient: Ab initio calculations
of calcium ion concentrations. Annals of Clinical and Laboratory
Science 1992;22:40-50.
R. Bertholf
Professor of Pathology
University of Florida Health Science Center/Jacksonville
> -----Original Message-----
> From: Clinical biochemistry discussion list [mailto:ACB-CLIN-CHEM-
> [log in to unmask]] On Behalf Of Trevor Gray
> Sent: Monday, December 15, 2008 2:43 PM
> To: [log in to unmask]
> Subject:
>
> Robert,
>
> What function are you looking for from the citrate?
> Citrate complexes calcium at a rate of two mols/mol Ca,
> but it is, of course, very rapidly metabolised in the
> liver. We did a lot of work during liver transplantation
> back in the days when blood transfusions were stored in
> ACD (C=citrate). The patients lost most of their ability
> to metabolise citrate when they were anhepatic (and the
> kidney function was also compromised by the clamps) so
> developed extremely high citrate concentrations and
> required a lot of added calcium to prevent the ionised
> calcium falling too low. Low ionised calcium and high
> potassium (also from the transfused blood) leads to
> cardiac arrest. The citrate does not interfere with the
> measurement of ionised calcium - any low value you see as
> a result of the citrate in the plasma will be because of
> complexed calcium which is not physiologically effective.
> Any patient with a normal liver will, however, rapidly
> metabolise the citrate as happened during transfusions
> with ACD preserved blood. The only problems noted in the
> literature from citrate seen in patients with intact liver
> function occurred in patients undergoing massive
> transfusion with peripheral (and presumably splanchnic)
> shutdown. A similar rise in citrate will
> occur in patients following dialysis. Whether this causes
> low ionised calcium will depend on the rate of infusion.
> You will probably only run
> into problems if there is poor hepatic function or
> shunting past the liver, but it will depend on the rate
> you are pumping the citrate in. A concentration of 3 to 5
> mmol/L circulating in the plasma will really drop the
> ionised calcium but presumably you are talking about the
> levels which are in the blood which is returned to the
> patient which will quickly be metabolised. If you want to
> know what the metabolic rate of citrate is, there is some
> work in the blood transfusion literature, but I can't lay
> my hands on the papers which are from at least 20 years
> ago.
> Gray TA, Buckley BM, Sealey MM, Smith SCH, Tomlin P,
> McMaster P. "Plasma ionized calcium monitoring during
> liver transplantation". Transplantation 1986; 41: 335-39.
>
>
> Trevor
> Dr. T.A. Gray
> Consultant Chemical Pathologist
> Northern General Hospital
> Sheffield S5 7AU
>
> On Mon, 15 Dec 2008 17:14:16 -0000
> Robert Daly <[log in to unmask]> wrote:
> > Hi all,
> >
> > We would like to use citrate based dialysis fluid in
> >dialysing certain
> > patients and are wondering if a citrate concentration of
> >3-5 mmol/L in
> > blood will interfere with the ionized calcium assay on
> >the Radiometer ABL
> > 825 analyser.
> >
> > we will measure ionized calcium
> > a) in the circuit to ensure the citrate dosing is
> >adequate ie adequate
> > anticoagulation
> >
> > b) in the patient to ensure the ionized calcium is not
> >too low ie citrate
> > toxicity
> >
> > Thanks in advance.
> >
> > Kind Regards,
> > Robert Daly,
> > Chemical Pathology,
> > Beaumont Hospital,
> > Dublin 9.
> >
> >
> >
> >
> >
> >
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