We analyse faecal electrolytes and osmolality fairly regularly and have a
fairly simple protocol.
Solid Samples:
Electrolytes:
1+2 dilution with H2O followed by homogenisation on a vortex, centrifugation
and analysis of fluid layer in Urine mode on a Vitros 250.
Osmolality:
Sample is rejected.
Fluid Samples:
Electrolytes:
Homogenise sample on vortex, centrifuge and analyse fluid layer on Vitros
250.
Osmolality:
Analyse fluid layer as above.
>From discussions with our gastroenterologists, the analysis of faecal
electrolytes and osmolality is basically useless in differentiating
secretory from osmotic diarrhoea unless there is a fairly significant
osmolar gap. Of course the one disorder where it is useful (if you measure
chloride) is the rare condition chloride diarrhoea.
I have no idea of the basis for the method involving boiling with HNO3 and
would not like to try it myself!
Hope this has been of help.
Peter Vervaart BAppSci MAIMS FAACB
Senior Scientist, Gastroenterology and Nutrition
Department of Clinical Biochemistry
Women's and Children's Health Care Network
Flemington Road
Parkville, Victoria, 3052
Australia
Phone: 613-9345 5906
Fax: 613-9349 1819
WWW: http://www.rch.unimelb.edu.au\biochem\gastro
----- Original Message -----
From: Lars Eikvar <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 28, 1999 10:06 PM
Subject: Method for determination of electrolytes in faeces
> Dear colleagues
>
> We are currently receiving requests for determination of Na and K in
feces.
> this analysis is only performed by one or two labs in Norway. The method
in
> use there is not very attractive, since it involves boiling in
concentrated
> HNO3.
>
> Have any of the list members any experience with alternative methods?
>
> According to my poor knowledge of the subject, determination of
> electrolytes can be of interest in discriminating between secretory and
> osmotic diarrhea. Does anyone have any views about the usefulness of this
> today?
>
> Kind regards
>
> Lars Eikvar
> MD, PhD
> consultant
> Department of clinical chemistry
> Ullevaal hospital
> Norway
>
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