Estradiol immunoassays – interference from the drug fulvestrant (Faslodex®) may cause falsely elevated estradiol results

Manufactured by Siemens Healthcare Diagnostics Inc. / Siemens Healthcare Diagnostics Ltd and Roche Diagnostics GmbH- assay interference from the drug fulvestrant (Faslodex®) may cause falsely elevated estradiol results. Both Siemens and Roche have issued field safety notices (FSNs) highlighting this issue. Estradiol assays from other manufacturers may also be affected by fulvestrant (Faslodex®) interference and this is currently under investigation (MDA/2016/004).


Action by Laboratory staff

  • Determine if estradiol immunoassays are used in your laboratory.
  • Continue to use affected estradiol immunoassays for patients not on fulvestrant.
  • If measuring estradiol levels in patients on fulvestrant consider alternative methods, such as Liquid Chromatography-Mass Spectrometry (LC-MS).
  • Consider the need to carry out a review of previously reported test results.
  • Monitor the MHRA website or subscribe to email alerts for any possible further FSNs on this issue.

Action by Healthcare personnel managing patients on this drug

  • When test requests include estradiol, state if the patient is on fulvestrant.
  • Consider reassessing the menopausal status of patients on fulvestrant by other means where necessary.

Deadlines for actions

Actions underway: 04 April 2016

Actions complete: 25 April 2016

Device details


Assay Test Code Catalog Number Siemens Material Number (SMN) Lot Number
ADVIA Centaur® Enhanced Estradiol1 eE2 10490889 10491445 10697757 10490889 10491445 10697757 All lots
Dimension Vista® LOCI Estradiol2 E2 K6463 10489099 All lots
IMMULITE®/ IMMULITE 1000 Estradiol E2 LKE21 LKE21(D) 10381132 10702832 All lots
IMMULITE® 2000 Estradiol3 E2 L2KE22 L2KE22 (D) L2KE26 L2KE26 (D) 10381178 10702833 10381177 10702834 All lots
  1. The same reagents are used on the ADVIA Centaur, ADVIA Centaur XP, ADVIA Centaur XPT and ADVIA Centaur CP systems.
  2. The same reagents are used on the Dimension Vista 500 and 1500 systems.
  3. The same reagents are used on the IMMULITE 2000 and IMMULITE 2000 XPi systems.


Product Name Product Description GMMI / Part No Lot Number
Estradiol II Elecsys Estradiol II assay Estradiol II 03000079190 All lots
Estradiol III Elecsys Estradiol III assay Estradiol III 06656021190 All lots

Please note oestradiol is used interchangeably with estradiol.

Problem / background

Siemens and Roche both manufacture a number of estradiol assays and have communicated that the drug fulvestrant (Faslodex®) may cause falsely elevated estradiol results in assays. Fulvestrant has a similar chemical structure to estradiol and may cross-react with the antibodies used in immunoassays.

Fulvestrant is indicated for the treatment of postmenopausal women with oestrogen receptor positive breast cancer, locally advanced or metastatic breast cancer for disease relapse on or after adjuvant anti-oestrogen therapy, or disease progression on therapy with an anti-oestrogen. If the listed estradiol assays are used for this group of post-menopausal women, falsely elevated estradiol results could lead to misinterpretation of the menopausal status of these women. This may result in treatment with fulvestrant being altered.

Manufacturer contacts

ADVIA Centaur ®

Siemens Healthcare Diagnostics Inc.
511 Benedict Avenue
Tarrytown, NY 10591, USA
Tel: Please see below
Email: Please see below

Dimension Vista ®

Siemens Healthcare Diagnostics Inc.
500 GBC Drive
Newark, DE 19714, USA
Tel: Please see below
E Mail: Please see below

Phone contact for the above USA based manufacturers in the UK (European Authorised Representative).

Siemens Healthcare Diagnostics Limited
Newton House, Sir William Siemens Square
Frimley, Camberley
GU16 8QD

Tel: 01908 282 433



Siemens Healthcare Products Limited
Glyn Rhonwy
LLanberis, Caernarfon, Gwynedd, LL55 4EL

Tel: 01286 871 871


Estradiol II/ Estradiol III

Stefanie Koehler
Roche Diagnostics GmbH
Sandhofer Strasse 116

Tel: +49 621 759-3511 Email:


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Send enquiries about this notice to MHRA, quoting reference number MDA/2016/004 or 2016/001/018/601/005.

Technical aspects

Caroline Olabisi, MHRA

Tel: 020 3080 6580


Clinical aspects

Dr Soundararajan Jagdish, MHRA

Tel: 020 3080 7187 Email:

Reporting adverse incidents in England

Through Yellow Card

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Northern Ireland Adverse Incident Centre, CMO Group,
Department of Health, Social Services and Public Safety

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NHS National Services Scotland

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Reporting adverse incidents in Scotland

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Reporting adverse incidents in Wales

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Estradiol immunoassays – interference from the drug fulvestrant (Faslodex®) may cause falsely elevated estradiol results MDA/2016/004

Published 24 March 2016