The problem with 24h urines is over or under collection. A 24h urine
creatinine should be measured on 24h urines to assess adequacy of
collection although urine creatinine and possibly urine catecholamines
may be influenced by muscle bulk. Therefore the standard teaching of 3
x 24h urine collections still pertains. However this is usually not
done.
We screen using 24h urine catecholamines and all raised or borderline
normal values with a raised urine noradrenaline to creatinine ratio are
also analysed for urine metadrenaline and normetadrenaline.
However the problem of borderline results still poses a diagnostic
problem because these assays have a sensitivity 65-74% and specificity
95%.
Jeffrey
Dr Jeffrey Barron
Consultant Chemical Pathologist
St Helier Hospital
Carshalton
Surrey SM5 1AA
UK
Tel UK 20 8296 2660
Fax UK 20 8641 2633
[log in to unmask]
>>> John Kane <[log in to unmask]> 04/16/02 11:47am >>>
Date sent: Tue, 16 Apr 2002 08:42:22 +0100
Send reply to: "Robertson, Stuart"
<[log in to unmask]>
From: "Robertson, Stuart"
<[log in to unmask]>
Subject: Urine catecholamines
To: [log in to unmask]
> I am interested to know how laboratories interpret 24 hour urine
> catecholamines (particularly noradrenaline) in adults being
investigated for
> possible phaeochromocytoma.
>
> To exclude phaeochromocytoma as a likely diagnosis, are any labs
using a
> 'cut-off' level which is different from an 'upper limit of normal'
derived
> from data from a population of 'normal' healthy individuals? If so,
what
> cut-off level is appropriate?
>
> Stuart Robertson
> Biochemistry Department
> Hull Royal Infirmary
> Hull
> HU3 2JZ
> UK
>
> (01482-607707)
Stuart
To set up our "reference range" for urine catecholamines and
metadrenalines we analysed the results of a large number of urine
samples from hypertensive patients referred to us for the
investigation of possible phaeochromocytoma. We removed the
results of any patient subsequently shown to have a
phaeochromocytoma and to be sure that we did not include any
unknown phaeos we truncated the top 2% of the rest of the results.
This gave us ranges of :-
Noradrenaline <1.0 umol/24hrs
Adrenaline <0.2 umol/24hrs
Normetadrenaline <4.0 umol/24hrs
Metadrenaline <2.0 umol/24hrs
This range is based on catecholamine / metadrenaline levels in
treated and untreated hypertensive subjects and should therefore in
theory be more appropriate for the population being investigated.
John Kane
Mr. John Kane
Clinical Biochemistry Dept
Hope Hospital
Salford
M6 8HD
Tel. 0161 787 4374
Fax. 0161 788 7443
Email [log in to unmask]
Website :- http://www.johnsgarden.co.uk/
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