 |
 |
I did a bit of a search a while back when being pressed for the same service and found the attached references. I am not convinced of the efficacy of the test, but feel somewhat obliged to offer it as we hosted obstetric SpRs who had written one of the papers. I would also comment that the demand has declined recently. with best wishes Richard Richard Mainwaring-Burton Consultant Biochemist Queen Mary's Hospital Sidcup, Kent 020-8308-3084 -----Original Message----- From: Jonathan Middle [mailto:[log in to unmask]] Sent: 30 March 2009 15:12 To: [log in to unmask] Subject: Re: Progesterone levels in PUL Hi Current immunoassay methods do not agree with one another, yet manufacturers may claim that they are all standardised using GCMS. Whether they are metrologically traceable to a certified progesterone standard depends on which elements of the traceability chain they have employed in the process. Furthermore, if analytical specificity is not optimal, then traceability is not possible and results will not be comparable. There is only one way properly to assess these methods. Create a panel of off-the-clot, single donation, unprocessed, native human sera with a range of endogenous progesterone values; have their progesterone concentrations assigned by ID-GCMS by a member of the steroid reference laboratory network; run a spit sample comparison with the method in question. If the slope is 1.0 then the method is correctly calibrated. If the scatter about the regression line is small, specificity is adequate. If the intercept is small, baseline security is good. When I have done this with a limited number of UK NEQAS pools, it is possible to see clear method differences. My last exercise (published in my 2008 Annual review) is attached. I do not distribute pregnancy sera with high levels, but the following data may also be helpful: At distribution 348 I distributed a pool with an ALTM of 40.7 nmol/L (CV 10.9%) The overall range of results (excluding outliers) was 25 - 58 nmol/L Trimmed method means were: Siemens Immulite 2000/2500: 33.0 nmol/L (n=34, CV 8.2%) Roche Elecsys/E170 Modular: 38.9 nmol/L (n=83, CV 5.7%) Abbott Architect: 40.9 nmol/L (n=54, CV=4.9%) Siemens ADVIA Centaur: 44.0 nmol/L (n=82, CV=6.7%) Beckman Access: 47.0 nmol/L (n=26, CV=10.6) This shows that any clinical cut offs must be made method-specific or mis-classification may occur. I had a poster on progesterone interpretation at Focus2007 - see attachment - which showed what labs were doing in terms of use of progesterone in assessment of fertility. Hope this helps. Jonathan Dr Jonathan Middle Deputy Director, Birmingham Quality (UK NEQAS) Organiser UK NEQAS for Steroid Hormones 0121 414 7300, fax 0121 414 1179 ________________________________ From: Clinical biochemistry discussion list on behalf of Avril Wayte Sent: Mon 30/03/2009 14:22 To: [log in to unmask] Subject: Progesterone levels in PUL Dear colleagues In 2006 I asked a question on the mailbase regarding the usefulness of progesterone in women with pregnancy of unknown location (PUL), and received a number of responses. I am asking the same question again, as the topic has reared it's head again at our Trust. It seems to be accepted in theory that lower progesterone levels in these women suggests a non-viable pregnancy. However, my question relates to what the cut-offs for progesterone should be. We use the Roche E170 progesterone method, and I cannot find any literature that provides my answer. I have spoken to Roche at length in 2006 (and waiting for a current response) and they tell me that their method is standardised against the ID-GC/MS method so that all standarised methods should use the same cut-offs. Unfortunately, the papers that I have come across do not go into this sort of detail, and all seem to use different ranges! I wonder if any of you E170 users out there are using progesterone for this purpose, and whether you would be prepared to share details of your practice with me? In anticipation Avril Avril Wayte Consultant Biochemist Ysbyty Gwynedd Bangor North Wales ------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/ ------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/