Just one quick point about what is meant by 'reference labs' in Sandra's posting
In the US, 'reference labs' are often quite large operations performing a wide range of specialist tests that may not usually be done by smaller local labs. They are what we would perhaps call 'referral labs'. They will be using the same large scale automated equipment that large labs here use.
They are not Reference Laboratories in the sense of laboratories which maintain Reference Methods (eg ID-GCMS, atomic absorption, IFCC enzymes etc) and which collaborate within reference laboratory networks to ensure that their trueness, traceability and comparability are optimal.
We need to use the latter to help produce patient-like materials with reference method target values which can then be used to assess and evaluate the trueness and calibration of 'routine' tandem mass spectrometry methods as they are developed. Linda Thienpont, Lothar Siekmann and I have been recommending this for decades for immunoassay.
Cheers
J
Dr Jonathan Middle
Deputy Director, UK NEQAS Birmingham
0121 414 7300, fax 0121 414 1179
-----Original Message-----
From: Clinical biochemistry discussion list on behalf of Sandra Rainbow
Sent: Thu 20/09/2007 13:59
To: [log in to unmask]
Subject: Re: Summary of Testosterone levels in pregnancy[Scanned]
In support of Jonathans summary about the poor performance of immunoassays for steroids and in particular testosterone in females and children, I have just returned today from the Asilomar Mass Spectrometry meeting organised by the American Society of Mass Spectrometry on the relevant topic of Clinical Applications of Mass Spectrometry. Testosterone analysis was discussed in detail by Dr William Rosner, MD, St. Luke's-Roosevelt Hospital Center & College of Physicians and Surgeons, Columbia University who has chaired a committee for the American Endocrine Society on the measurement of testosterone and its lack of value and transferability of results by modern immunoassay methods. The summary of the position statement can be viewed at the following
http://jcem.endojournals.org/cgi/content/abstract/92/2/405
In the US there are a large number of reference labs producing their results by LC Tandem Mass Spectrometry and the text books will have to be rewritten with the correct results. Reports to NEQAS indicate that there are at least 4 labs in the UK that have seen the light. The biggest challenge is getting universal standardisation so that we are all able to report against an accepted standard
I wonder when the European Endocrine societies will focus on this topic and appreciate the poor quality of the results being produced by immunoassays
regards
Sandra
Dr Sandra Rainbow
Consultant Clinical Scientist
Department of Clinical Biochemistry
NWLH
020 8869 2120
-----Original Message-----
From: Clinical biochemistry discussion list
[mailto:[log in to unmask]]On Behalf Of Jonathan G. Middle
Sent: 20 September 2007 12:17
To: [log in to unmask]
Subject: Re: Summary of Testosterone levels in pregnancy[Scanned]
Thanks Helen
I think that as soon as we have reliable routine mass spectrometry methods with analytical parameters and calibration underpinned by a network of ID-GCMS reference laboratories, we will have to systematically re-examine what 'true' values are for hormones in health and disease - steroids in particular. We are already starting to see that 'true' testosterone levels in women may be half that which we currently think of as 'normal'. This doesn't mean that the testosterone that is there is half what we thought, but that the methods that gave us these values are 100% 'out' - you know what I mean!
We cannot rely on or easily compare studies where non-extraction immunoassay has been used, because of poor analytical sensitivity, non-specificity, uncertain calibration, and manufacturer 're-formulations' which occur from time to time.
A concerted effort is needed to establish 'best practice' protocols for tandem mass spectrometry methods for steroids, so that we can build this knowledge base. There will be some sessions at Focus 2008 on this subject.
I am already seeing a growing group of labs amongst UK NEQAS participants using Tandem Mass Spec. Interestingly, some of these labs have very poor consistency of bias performance scores against the ALTM, because they get high negative bias for endogenous samples and high positive bias for spiked samples. This is because they are probably getting the right answer and also have quantitative recovery (see below).
For UK NEQAS participants I have recently uploaded to the participants website some reports on three recent distributions of oestradiol, progesterone and cortisol samples with ID-GCMS target values. (Some of my 2006 data on Testosterone in females were included within John Kane's paper in the Annals this year.) These exercises reveal that some methods are 'spot on' but others are 'miles out'.
I have also just reported and uploaded to the participants website, results of my annual classical recovery exercises. These do not make very comfortable reading if you share with me the belief that recovery is an important indicator of analytical validity.
I have also performed an exercise on recovery of the SHBG IS (not yet uploaded to the website but coming soon), which showed method differences (range 80 - 120%) which correlated quite well with median UK NEQAS method bias. By serendipity the median recovery of the 40 labs surveyed was 100%, so for this analyte, the ALTM may very well be 'right'.
The presence of large differences between testosterone and SHBG methods renders the reliability of indices derived from combining these parameters somewhat suspect, and comparison between publications using different combinations of methods but maybe using the same reference ranges for these indices, pretty nearly impossible.
Cheers
Jonathan
Dr Jonathan Middle
Deputy Director, UK NEQAS Birmingham
0121 414 7300, fax 0121 414 1179
-----Original Message-----
From: Clinical biochemistry discussion list on behalf of Grimes, Helen, UCHG
Sent: Wed 19/09/2007 18:41
To: [log in to unmask]
Subject: Summary of Testosterone levels in pregnancy
I posted the following "What is acceptable testosterone level in pregnancy since SHBG increases. It specifically arises when we were asked to do a testosterone level on a hirsute 16/40 pregnant lady. Her testosterone is 5.5 nmol/L (Ref 0.5-2.6) with a SHBG of 310 nmol/L (Ref 26-110 - non pregnant)."
Several replies, and in general it was considered "Normal" for pregnancy and if one calculated a FAI (though its applicability was queried) then the FAI was normal. Some had seen higher in normal pregnancies. Apparently Sophie Barnes has some data generated when she worked with Mike Wheeler, but it is unpublished, which is a pity.
Of interest in the replies was the fact that hairiness is common in pregnancy. It was queried and rightly so, as to whether it was a true testosterone, we use Centaur, and so far agreement with Mass Spec with Leeds for high levels but not for moderately elevated levels).
The fact that PCOS women are know to have higher androgen levels during pregnancy See Human Reproduction Vol 17, No 10, pp2573-2579, 2002, T.Sir-Petermann et al Maternal serum androgens in pregnant women with PCOS; possible implication in prenatal androgenization. Method here stated to be DPC Radioimmunoassay.
Finally the referring Consultant was anxious regarding a publication that elevated Testosterone in pregnancy could affect offspring size, and someone gave me the reference. Maternal testosterone levels during pregnancy are associated<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
with offspring size at birth. S M Carlsen et al. European Journal of Endocrinology (2006) 155 365-370 ISSN 0804-4643
Online version via <http://www.eje-online.org> www.eje-online.org. Immulite method for SHBG and Orion Diagnostics for Testosterone.
I have not read the latter paper in detail, but if an increase in Testosterone and SHBG are "normal", was the last paper based on a chance finding, and what was being measured anyway?? So more questions??
All the best
Helen.
------------------------------------------------------------------------------------------
Dr Helen Grimes, Dept Clinical Biochemistry, University College Hospital, Galway, Ireland
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via the internet. Views expressed are those of the individual and
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