Well here is the evidence Jonathan...although as it is quite an old reference it does not conform to STARD criteria!!!
Julian
Morgan DB, Carver ME, Payne RB. Plasma creatinine and urea: creatinine ratio in patients with raised plasma urea.Br Med J. 1977 Oct 8;2(6092):929-32.
We examined the plasma urea and creatinine concentrations and the ratio between them according to diagnosis in 100 unselected and 31 selected adult hospital patients with a plasma urea concentration greater than or equal to 10 mmol/l (60mg/100ml). We also examined plasma urea and creatinine concentrations in 350 unselected consecutive patients, but found no useful relation between the two values. Congestive heart failure was the most common identifiable cause of a raised plasma urea concentration in the 100 unselected patients (36%). Among these 100 patinets the plasma creatinine concentration was a more useful discriminant between prerenal uraemia and intrinsic renal failure than was the urea:creatinine ratio or the plasma urea concentration. A plasma creatinine concentration greater than 250 mumol/1 (2-8 mg/100ml) indicated intrinsic renal failure with a 90% probability.
>>> Eric Kilpatrick <[log in to unmask]> 09/10/2006 08:35 >>>
Jonathan
More than any of us you know that 'absence of evidence' does not mean 'evidence of absence'.
Make it a case of champagne and we may get a bit more interested in answering the question!
Kindest regards
EricDr. Eric S. KilpatrickConsultant in Chemical PathologyDepartment of Clinical BiochemistryHull Royal InfirmaryAnlaby RoadHull HU3 2JZTel 01482-607708Fax 01482-607752
> Date: Sun, 8 Oct 2006 10:54:59 +0100> From: [log in to unmask]> Subject: Re: feedback on U and E profile question> To: [log in to unmask]> > Thanks.> > Our findings on the effects of varying what is included in some > common groups was published in a Focus abstract:> Reduction of workload by redefinition of test profiles> McVittie,J.D., Kay,J.D.S., Keenan,J.*> Annals of Clinical Biochemistry (1988); 25, S1, 188-189> > Is there any evidence that measuring plasma urea reliably detects the > state of hydration? I challenge students every year with this, but > the bottle of champagne remains unopened. "Everyone knows it" doesn't > win the prize.> > Jonathan> > On 6 Oct 2006, at 16:37, Myers Martin (Dr) wrote:> > > Dear all,> >> > Feedback to the question:> >> > "Should urea be dropped from the U&E profile and replaced with a Renal> > Profile consisting of sodium, potassium, creatinine and eGFR?"> >> > The comments ranged from an emphatic "No" to "[we have been doing > > this on out-patients and GP patients] since 1994"> >> > There was no consensus. Several still found urea useful in > > assessing pre-renal uraemia and hydration. Others clearly thought > > that it had no use as a general test in primary care.> >> > My interpretation of feedback:> > 1. There may be some merit in dropping urea from routine primary > > care U&E requests but the money saved would be relatively small.> > 2. I have sympathy for the thoughts of person 6 in the feedback > > below. Presumably in the USA this has all been sorted with > > centrally defined profiles.> > 3. I'm glad I didn't ask about the merits of ALT, AST and gamma GT > > in a liver profile.> >> > Regards> >> > Martin> >> >> > Feedback from Mailbase:> >> > 1. Urea is very useful for identifying dehydration when creatinine > > may not> > be raised.> >> > 2. We tried to drop ureas about 20 years ago in XXXX but there all> > the cases that needed urea: ITU, A&E, patients > 75 yrs, babies etc > > etc> > Too difficult in sample reception then. But now with EPR and order > > comms (for the lucky ones) it should be easy> > to drop most ureas.> >> > 3. No!> >> > 4. We did this for primary care a year or more ago, but have been> > unable to convince our secondary care colleagues to do likewise.> >> > 5. We only do urea on in-patients. This has been the case since > > 1994. I dropped it from the out-patient & GP work at that time. It > > remains available on request, but these are very few. We have been > > reporting eGFR since April, so in effect we are in line with your > > proposals apart from in-patient work.> >> > 6. There is too much local choice on what should be included in a > > profile. There is a requirement to have national definitions. This > > would be based on best evidence, will unify practice across the > > country and will give clarity for future tariffs and reimbursements.> >> > 7. Current practice in XXXXX:> > Primary care: Plasma sodium, potassium, creatinine, eGFR (18 y and> > over).> > Secondary and tertiary care: Plasma sodium, potassium, creatinine.> > Summary of current UK practice is in one of the Keele benchmarking> > reports.> >> > 8. We did this years ago for GPs,tho' have persisted in including > > urea for hosp> > requests,couldn't persuade hosp users to drop it at the time,tho' > > might be> > worth another go,partic now we have eGFR.> >> > 9. Sounds more logical> >> > 10. and you pick up pre-renal uraemia how? eGFR is irrelevant in > > the elderly> > hospital in-patients who of course will have low creats due to low> > muscle mass. is it worth the grief? 4 part renal profile: Na+, K+, > > Urea,> > creat. Diminiution of info is not a service.> >> > 11. Personal view: urea gives me valuable information about > > hydration> > Status. For example in a 65 year old patient with a history of > > vomiting:> > Na 145 K 5.0 urea 20.1 creatinine 140 suggests dehydration and may > > be GI> > bleed.> > Na 145 K 5.0 urea 5.5 creatinine 140 suggests normal hydration and > > some> > renal impairment.> > As DB and on ward rounds including ICU I find urea in the 'U/E' very> > helpful. It is a useful adjunct to creatinine and/or eGFR giving> > different information and should not be dropped in my view..> > ------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/
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