I would like to thank Dr Handley and Dr Perry for raising
this point.
The assay is calibrated by a two-point recalibration
against a stored master curve.
We evaluated the kit and the CV at lower end of normal
range and it was 15.3%, which encouraged us to use it.
There are also few studies that support the use of PRC
(using similiar methods) for screening for primary
hyperaldosteronism and they claim a superior sensitivity
to PRA.
http://www.clinchem.org/cgi/content/full/50/9/1650
http://www.eje-online.org/cgi/reprint/150/4/517
http://ndt.oxfordjournals.org/cgi/content/full/19/4/774
The protocol we use is as follows:
The results of the PRC are interpreted in conjunction to
the Plasma aldosterone and the use the cutoff value of 80
PA/PRC (pmol/mU) as an indicative for further
investigation.
If PA/PRC>80, a saline loading test and the frusemide test
are performed.
In salt loading test a low PA level <236 pmol/l makes APA
or IHA unlikely.
After rennin stimulation using frusemide we use a cutoff
value for PAC of 14 mU/L.
My question is: If we are using the above mentioned
protocol can we still miss cases of APA?( Those with
markedly reduced plasma renin).
In other words; Is it possible to have a patient with APA,
with markedly reduced plasma rennin (< 2.8 mU/L) and low
plasma aldosterone to get a low ratio of PA/PRC so we miss
the diagnosis?
I will be grateful for advice.
Best regards
Mohamed
On Tue, 6 Nov 2007 16:13:46 -0000
Perry Les <[log in to unmask]> wrote:
> To add my twopence worth, like Pat Kyd we looked at the
>Diasorin renin
> mass kit and decided not to proceed with using it as a
>routine assay
> service.
>
> Reasons:
> 1. We had to dilute calibrator 1 with the 0 calibrator
>to generate
> a standard that could at least detect the lower end of
>the 'normal'
> range.
> And
> 2. Even so, this did not distinguish the true Conn's
>syndrome
> patients from patients with low but normal renin mass
> concentrations
>
> I am also interested to note in the data sheet that
>there is no
> imprecsion data on low plasma renin mass concentration,
>what is the
> imprecision with renin mass concentrations of eg 2.0
>uiU/ml. I also note
> that the lw end of the supine ref range is 2.8 uiU/ml
>and that further
> down the functional sensitivity is quoted as 1.96
>uiU/ml. Can the assay
> truly differentiate normal low renin from true Conn's
>syndrome?
>
>
> Dr Les Perry
> Principal Clinical Scientist
> Department of Clinical Biochemistry
> Barts & The London NHS Trust
> Pathology & Pharmacy Building
> 80 Newark Street
> Whitechapel
> London E1 2ES
>
>
>
> -----Original Message-----
>From: Clinical biochemistry discussion list
> [mailto:[log in to unmask]] On Behalf Of
>Mohammed El
> Sammak
> Sent: 06 November 2007 11:54
> To: [log in to unmask]
> Subject: Re: Immunoassay for Renin (Mass)
>
>
> We are using the Diasorin kit on the liaison immunoassay
> analyzer since about 6 months.
> The assay is givnig good results in the Biorad EQAS.
> Attached is the insert sheet for Renin on the Liaison
> immunoassay analyzer.
> Regards
>
> Mohamed Elsammak
> Consultant Chemical Pathologist
> King Fahd Specialist Hospital
> Dammam
> KSA
>
>
> On Tue, 6 Nov 2007 10:59:43 +0000
> Graham handley <[log in to unmask]> wrote:
>> Hi
>>
>> Our Endocrinologist has recently attended a meeting
>>where the virtues of
>> measuring Renin mass by an immunoassay were extolled.
>>
>> Does anyone have any information as regards such an
>>assay, either as to
>> manufacturer of kits or to a Laboratory offering the
>>service?
>>
>> Many thanks
>>
>> Graham
>>
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