I have already raised this with the originators, but on reflection, I can see that one might be somewhat questioning of the scanned paraprotein levels if the albumin contribution to the total protein is discrepant. This might lead me to question the comparative stain signal strength vs quantitation for other proteins as well. 
 
On further reflection though, I regard scanning densitometry using non-specific stains as more art than science, and don't dare to claim too many decimals for the mathematical results produced, especially as the marking of peaks is a secondary art superimposed on the art of staining and scanning.
 
Having got to think it through properly perhaps the following are also relevant reflections :
   1. How many of us have checked the linearity of the staining methods we use for any globulins and does this include massive paraprotein levels ?
   2. Are we sure of the linearity of other protein binding assays (BCG, BCP, turbidimetry, immunofluorescence included) at abnormal levels ?  We have found significant serious hook effect on Olympus IgA and IgM assays.  We are currently working on a protocol to spot such problems.
 
In the light of these, are we justified in claiming the precision and accuracy to the level we appear to be worried about ?

with best wishes

Richard

Richard Mainwaring-Burton
Consultant Biochemist
Queen Mary's Hospital
Sidcup, Kent
DA14 6LT
020-8308-3084

-----Original Message-----
From: Ian Barlow [mailto:[log in to unmask]]
Sent: 26 May 2004 15:44
To: [log in to unmask]
Subject: Re: Hydrasys LC Sebia albumin vs. Beckman Coulter albumin

I am unclear as to why you need to use the Sebia albumin. Why not simply use the more precise BCG/BCP colorimetric albumin, to help determine the globulin concentration, followed by scanning densitometry to measure the paraprotein concentration?
 
Ian Barlow 
Scunthorpe 
UK 
-----Original Message-----
From: Miall Philip [mailto:[log in to unmask]]
Sent: Wednesday, May 26, 2004 3:29 PM
To: [log in to unmask]
Subject: Re: Hydrasys LC Sebia albumin vs. Beckman Coulter albumin

We consider that the discrepancy has become more marked since the recent change in formulation of the Sebia Amido Black stain.
Discrepancy is particularly wide where high globulin levels occur, either polyclonal or monoclonal.
 
The previous amido black formulation appeared to us to be far better, usually the difference was not more than 2g/L and very occasionally up to 5 g/L. Now we find that 4-5g/L are the norm and up to 10g/L can occur.
 
Our albumins are measured routinely on the Olympus A640 system.
 
We have already discussed our concerns with Sebia Reps in UK.
 
Philip Miall (Principal Biochemist) & Alan Williams (Consultant Biochemist)
 

Philip

Philip Miall
Principal Biochemist
Clinical Biochemistry
Royal London Hospital

Telephone 020 7377 7000  (extension 2250 at RLH)
14-2250

-----Original Message-----
From: Bakkeren, DL [mailto:[log in to unmask]]
Sent: 26 May 2004 13:36
To: [log in to unmask]
Subject: Re: Hydrasys LC Sebia albumin vs. Beckman Coulter albumin

I can confirm that the Roche Albumine BCG and Sebia amido black method have the same discrepancy. The regression equation according to Passing and Bablok is:
Sebia ALB amido black =1,384 * Roche ALB BCG - 10.7. So the concentrations in the normal range are higher with Sebia than with Roche, though our regression line is tilted in comparison with yours, giving progressively higher values on higher concentrations.
Of course it is known that different analytical assays measure different aspects of molecules. Different dyes measure different molecular markers. That is even so with differente amido black formulations!
 
Kind regards,
 
Dr. Dirk Bakkeren
Clinical chemist
Clinical laboratory
Máxima Medisch Centrum locatie Eindhoven
(  +31 40 888 8900
*  [log in to unmask]
-----Oorspronkelijk bericht-----
Van: Sean Maguire [mailto:[log in to unmask]]
Verzonden: maandag 24 mei 2004 16:31
Aan: [log in to unmask]
Onderwerp: Hydrasys LC Sebia albumin vs. Beckman Coulter albumin

Dear colleagues,
Could I get some feedback on what you think of this comparison of albumins on the Sebia electrophoretic system vs. albumins on the Beckman Coulter LX20Pro.
There appears to be a large steady positive for the Sebia method. 
Many thanks,
Sean Maguire
Mater Hospital
Dublin 7
[log in to unmask]
 
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------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 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 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 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 List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/