Having attended discussions on the topic, read some of the literature,
followed discussions on the mailbase and old enough to formulate an opinion
(and young enough to state it); I am not yet convinced about the clinical
utility of free testosterone measurement. Yes, a priori, it makes sense;
however, the literature on this topic is lacking. We can discuss and quibble
about which method is better but there is limited information on the test's
clinical utility part of it coming from the fact that the gold standard test
is not the best itself.
David Alter, MD
Clinical/ Chemical Pathologist
Pathology and Laboratory Medicine
Spectrum Health-Blodgett
-----Original Message-----
From: Les Culank [mailto:[log in to unmask]]
Sent: Monday, July 28, 2003 12:26 PM
To: [log in to unmask]
Subject: FW: "free Testosterone" - 2 wrongs don't make a right, do they?
----------
From: Les Culank <[log in to unmask]>
Date: Mon, 28 Jul 2003 17:25:00 +0100
To: John Kane <[log in to unmask]>
Subject: Re: "free Testosterone" - 2 wrongs don't make a right, do they?
Wasn't it Richard Nixon who said "if 2 wrongs don't make a right, try 3"?
Would he have compounded the uncertainty of testosterone assay, & the
uncertainty of SHBG assay, with the uncertainty of adding on a so-called
"free testosterone" calculation.
Our clinical colleagues here generally accept that serum SHBG is not a
worthwhile routine request with testosterone, neither in theory nor in
practice (nor even in the popular usage of neurone-free test protocols).
In the context of Taieb's paper referred to below, & at:-
http://www.clinchem.org/cgi/reprint/49/8/1381.pdf
is it time not only for a major focus on testosterone assays, as suggested,
but also to reconsider what place (if any) SHBG should have with them?
Best wishes,
Les
> From: John Kane <[log in to unmask]>
>
> I totally agree with Jonathan that a concerted effort is now needed to
sort
> this problem out. Everybody who measures testosterone in female samples
> should at least read the article in Clinical Chemistry and ask searching
> questions of their suppliers as to the validity of their assays. For
whatever
> reason (poor precision, cross reaction etc.) many of the female
> testosterone results obtained using direct assays are wrong (usually
> resulting in incorrectly high levels being reported). I think that in the
> first
> instance laboratory staff can help by ensuring that no female testosterone
> results which may indicate serious pathology (>5.0 nmol/l) are sent out
> without being confirmed by an extraction technique. In the Clin Chem
> article even these techniques were shown not to be ideal but in our hands
> the extraction assay gives lower results (to a greater or lesser degree)
than
> the direct method in nearly all samples. Some samples with results >5.0
> nmol/l by the direct method end up back in the reference range (<2.4)
after
> extraction. Of course those patients that still have a high testosterone
level
> after extraction are the ones that need further investigation.
>
> John Kane
>
>
>
>
> Date sent: Mon, 28 Jul 2003 14:10:17 +0100
> Send reply to: JG MIDDLE <[log in to unmask]>
> From: JG MIDDLE <[log in to unmask]>
> Subject: Testosterone assays better than guessing?
>> Listmembers who have agonised over which testosterone assay to use in
>> women should be aware that a random number generator may be just as
>> useful!
>>
>> The latest edition of Clinical Chemistry includes an article
>> describing a major comparison study of commercial immunoassays with
>> ID-GCMS (the reference method), and an Editorial deploring the current
>> state-of-the-art of testosterone assays.
>>
>> Go here for links
>> http://www.ukneqas.org.uk/saf01.htm
>>
>> To those who have followed the UK NEQAS ID-GCMS exercises over the
>> years (you can download a pdf of the latest one for testosterone from
>> the SAF link), these findings will come as no surprise.
>>
>> A major collaborative effort between laboratory, clinical and industry
>> personnel is needed to address this issue.
>>
>> Useful discussions were had at the UK NEQAS SAF meeting last December;
>> more concerted action is needed now.
>>
>> Jonathan Middle
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