Alternatively if no direct ISE available :
Measure glucose and osmolality
Cross-check calculated vs measured osmolality for an easier calculation, since osmolality is a colligative property which ignores the non-aqueous (protein or lipid) volume.
Approximate calculation : (see internet for variants)
Osmolality = 2(Na + K) + gluc + urea
Calculated should be +/- 5 different.
If calculated much lower than measured, assume pseudohyponatraemia.
with best wishes
Richard
Richard Mainwaring-Burton
Consultant Biochemist
South London Healthcare Trust
Queen Elizabeth Hospital, Woolwich
Princess Royal Hospital, Farnborough
Queen Mary's Hospital, Sidcup
020-8836-5724
mob: 07831-739876
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of COLLINS MICHAEL (RM1) Norfolk and Norwich University Hospital
Sent: 31 July 2013 16:56
To: [log in to unmask]
Subject: Re: Spurious hypocalcaemia and hyperphosphataemia
We check sodium on all samples with total protein > 90 g/L or lipaemia index (Abbott Architect) >1.0 using a direct electrode.
A sodium of <125 will reflex total protein.
Mike Collins
BMS3
Biochemistry Automation
Norfolk & Norwich University Hospital
England
[log in to unmask]
http://www.nnuh.nhs.uk/
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of John Martin
Sent: 31 July 2013 15:51
To: [log in to unmask]
Subject: Re: Spurious hypocalcaemia and hyperphosphataemia
The pseudohyponatremia is not due to hyperviscosity per se but due to the reduced amount of water per litre of plasma as a consequence of a total protein of 112 g/L. One gram of protein has a partial volume of solution of ~ 1ml; hence one litre of plasma contains ~ 940ml of water assuming a 'normal' total protein of 60g/L. A litre of plasma with a total protein of 112g/L will contain ~ 888 ml of water therefore the [Na] in the water phase will be ~ (127/888)*940=134; the value obtained on the gas analyser direct ISE.
Regards
John Martin
Sent from my iPad
On 31 Jul 2013, at 14:05, "Veronique Stove" <[log in to unmask]> wrote:
> May I ask a further question on the inferences seen with some myeloma patients?
>
> We have a myeloma patient with the following results:
>
> Tot. Protein 112 g/L
> IgG 78,7 g/L
> Na 127 mmol/L K 3,6 mmol/L (indirect ISE) Cl 98 mmol/L Ca 2.05 mmol/L
> Phosph 0.85 mmol/L Osmolality 280 mOsm/kg
>
> Here, we probably have a pseudohyponatremia due to hyperviscosity. How are others dealing with this low sodium result? Do you advise to measure via direct ISE? Prior to centrifugation, we analysed this sample on our bloodgas meter, with 134 mmol/L as a result.
>
> Kind regards,
>
> Veronique
>
> ----------------------------------------------------------------------
> Universitair Ziekenhuis Gent
> Klinisch Ondersteunende Sector
>
> Veronique Stove
> PharmD PhD - Klinisch bioloog 24u lab
> Klinische Biologie - Gebouw 2P8
> Interne brievenbus: 2P8-klinische biologie De Pintelaan 185 - B-9000
> Gent
>
> tel.: +32 (0)9 332 5871
> [log in to unmask]
> www.uzgent.be
> ----------------------------------------------------------------------
>
> -----Oorspronkelijk bericht-----
> Van: Clinical biochemistry discussion list
> [mailto:[log in to unmask]] Namens Fiona Davidson
> Verzonden: woensdag 31 juli 2013 10:42
> Aan: [log in to unmask]
> Onderwerp: Re: Spurious hypocalcaemia and hyperphosphataemia
>
> Thanks for all your responses.
>
> I think the consensus is delayed separation. On closer inspection this sample seems to have been taken on a Friday and received in the lab on Monday. I have no idea why we analysed the sample as our policy is to take out all affected tests if a sample has been left unseparated overnight.
>
> We have recently picked up a case of undiagnosed myeloma causing a spuriously raised phosphate, however, as this is a young, asymptomatic patient whose phosphate and calcium were back to normal on the next sample I think this would be an unlikely explanation.
>
> Thanks
>
> Fiona
>
> ------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.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.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/
This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom
they are addressed.
If you have received this email in error please notify the originator of the message. This footer also confirms that this
email message has been scanned for the presence of computer viruses but this should not be relied upon as a guarantee that the contents are virus free.
Any views expressed in this message are those of the individual sender, except where the sender specifies and with authority,
states them to be the views of the Norfolk and Norwich University Hospitals NHS Foundation Trust. The information contained in this e-mail may be subject to public disclosure
under the Freedom of Information Act 2000. Unless the information is legally exempt from disclosure, the confidentiality of this e-mail and your reply cannot be guaranteed
------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/
********************************************************************************************************************
This message may contain confidential information. If you are not the intended recipient please inform the
sender that you have received the message in error before deleting it.
Please do not disclose, copy or distribute information in this e-mail or take any action in reliance on its contents:
to do so is strictly prohibited and may be unlawful.
Thank you for your co-operation.
NHSmail is the secure email and directory service available for all NHS staff in England and Scotland
NHSmail is approved for exchanging patient data and other sensitive information with NHSmail and GSi recipients
NHSmail provides an email address for your career in the NHS and can be accessed anywhere
********************************************************************************************************************
------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/
|