This is an interesting case. Here is a suggestion
Hello Wolfgang
This is an interesting case. Here is a suggestion from the top of my head.
Apologies if already suggested or if they turn out wide of the mark.
It doesn't sound to me like assay interference although checking the urea on
another platform may be worthwhile.
Other than GI bleeding another cause of a high urea (and possibly plasma
urea/creatine ratio) can be a tissue catabolic syndrome. This, if I remember
correctly, was first reported following the 1st world war. (That was long
before I was around!)
This syndrome of course is more commonly associated with severe tissue
injury. However I suppose there could have been a marked respiratory
acidosis or such-like causing a degree of tissue damage in this case.
In the flow phase (7 days to a few weeks post injury) there is a marked
negative nitrogen balance. That will push up the urea, and usually the urea
excretion. Perhaps in your case although she is not clinically dehydrated
there could also have been altered renal dynamics, e.g. reduced blood flow,
enabling more urea to be reabsorbed relative to creatinine, amplifying the
effect.
I admit I don't know if a respiratory syndrome can be severe enough to cause
this, as the syndrome itself was described in severe trauma or infection. It
might be worth checking the renal urea output in any case: is it increased
or is the uraemia due to retention.
Regards
Steve
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-----Original Message-----
From: Wolfgang Schneider [mailto:[log in to unmask]]
Sent: 31 July 2008 14:18
To: [log in to unmask]
Subject: Réf. : Re: High Urea
Hi,
The method is the Roche Urease on a Hitachi 917 . The only interferences
listed in the package insert are monoclonal immunoglobulines, and we are
waiting for a serum sample for electrophoresis. I don't know if she's on
Rifampicin but that shouldn't interfere according to Young's effects.
Thanks
***************************************************************
Wolfgang Schneider, PhD, CSPQ, FCACB
Chef du service clinique de biochimie
Hôpital du Sacré-Coeur de Montréal
5400, boul. Gouin Ouest
Montréal, Québec H4J 1C5
Canada
Tél.: (514) 338-2222 x 2611
Fax : (514) 338-3171
Courriel: [log in to unmask]
***************************************************************
De :
Jonathan Kay
<[log in to unmask]>
Pour :
[log in to unmask]
cc :
Jonathan Kay
<[log in to unmask]>
Objet :
Re: High Urea
2008-07-30 16:39
(Don't have the database of interferences with me.)
What's the analytical method and platform?
Any suspect drugs. has she been on rifampicin?
Does she have any unusual immunoglobulins?
Best wishes
Jonathan
On 30 Jul 2008, at 21:28, Wolfgang Schneider wrote:
> Hi,
>
> We have a 61 year old female patient with acute respiratory distress
> syndrome in our ICU. Over the last 10 days the urea levels have
> steadily
> risen over 10 fold from 6 to 76 mmol/L, with creatinine holding
> steady at
> around 90 µmol/L so renal function does not seem to deteriorate .
> Hemoglobin is stable too, so it doesn't look like GI bleeding, and the
> patient is not overtly dehydrated eiter.
> I think that an interference substance ( which ? ) would not rise
> steadily
> over 10 days but either be present or not...
>
> Any suggestions for this rise ?
> ***************************************************************
> Wolfgang Schneider, PhD, CSPQ, FCACB
> Chef du service clinique de biochimie
> Hôpital du Sacré-Coeur de Montréal
> 5400, boul. Gouin Ouest
> Montréal, Québec H4J 1C5
> Canada
> Tél.: (514) 338-2222 x 2611
> Fax : (514) 338-3171
> Courriel: [log in to unmask]
> ***************************************************************
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