Hi Nick



We have seen similar cross-reactivities which have been forwarded to Roche Tech Support.



We received a sample on a 20yr old female (?PCOS) and got 5.3nmol/L on our Testo II assay on the Cobas e601, so sent it for TMS and got 1.6nmol/L (normal). Meanwhile GP had sent a subsequent sample, 10 days later, for which we got 1.2nmol/L on our Testo II assay. Retrieval and re-analysis of the first sample gave 6.2nmol/L on our Testo II assay.



Having spoken to GP, she had stopped Microgynon 3 days prior to the 1st blood sample – LH/FSH/E2 all normal, non-cocp levels but testo significantly elevated. Then 13 days after stopping Microgynon, testo normal.

Microgynon does not have noresthisterone but does have Levonorgestrel.



When we first did our Testo I to Testo II comparisons back in Mar 2010, I checked some normal young volunteers and found -

2 very high/discrepant results – one turned out to be pregnant and the other was on Loestrin. I checked two other COCPs (Cileste and Yasmin) but saw comparable results for the two assays.



So it’s not just norethisterone that interferes.



Regards

Gail



Dr Gail Curtis

Consultant Clinical Biochemist

Dept of Clinical Biochemistry

Glan Clwyd Hospital



Ffôn • Tel: (01745) 445293         (WHTN 1815 5293)



Bwrdd Iechyd Prifysgol

Betsi Cadwaladr

University Health Board



-----Original Message-----

From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Nick Unsworth

Sent: 21 June 2012 17:59

To: [log in to unmask]

Subject: Norethisterone interference



Dear all,



We recently had a case of a 24 year old female GP patient with a testosterone result of 11.8 nmol/L (run on a Roche Elecsys E170 Modular system). 



Her GP subsequently contacted us saying that the patient was due to start taking norethisterone (a synthetic progestogen) but may have started prior to the bloods being taken. A repeat sample was sent 4 weeks later (10 days off treatment) which gave a testosterone result of 0.5 nmol/L.



Roche provided us with information from their spiking experiments showing a cross-reactivity of 5%. UKNEQAS also carried out a spiking experiment in distribution 379 which showed that the Roche platform performed with a significant positive bias.



Has anyone else come across similar cases where norethisterone has given such dramatically elevated testosterone results?



Any information greatly appreciated.

Best wishes,



Nick Unsworth



Trainee Clinical Scientist

Clinical Biochemistry, UCLH

60 Whitfield Street

London

W1T 4EU



[log in to unmask]



------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

Green Laboratories Work

http://www.laboratorymedicine.nhs.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/



Betsi Cadwaladr University Health Board - Email Notice (2010)

You are advised to read (and print for future reference) the Betsi Cadwaladr University Health Board e-mail notice which can be found at this location

http://www.wales.nhs.uk/sitesplus/861/page/47229





Rhybudd Ebost (2010) - Bwrdd Iechyd Prifysgol Betsi Cadwaladr

Fe'ch cynghorir i ddarllen rhybydd ebost Bwrdd Iechyd Prifysgol Betsi Cadwaladr (a'i argraffu er mwyn cyfeirio ato yn y dyfodol).  Gellir dod o hyd iddo yn y lleoliad canlynol

http://www.wales.nhs.uk/sitesplus/861/tudalen/47230



------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

Green Laboratories Work

http://www.laboratorymedicine.nhs.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/