Siemens ADVIA Chemistry and Dimension/Dimension Vista products – risk of false low results due to interference with N-acetylcysteine

False low results may occur in a range of clinical chemistry tests in specimens drawn from patients treated with N-acetylcysteine (NAC) due to the interference with specific assays utilised by Siemens ADVIA instruments.


Action by pathology staff

  • Establish if affected Siemens ADVIA Chemistry and Dimension/Dimension Vista assays are used in your laboratory.

Action by all healthcare personnel managing patients on these drugs

  • Ensure all relevant members of staff receive the manufacturer’s Field Safety Notices (FSN) and that they understand the problem and the advice given by the manufacturer.
  • Continue to only use affected assays on patients that are not being treated with NAC.
  • Ensure bloods are taken prior to NAC treatment.
  • When requesting any of the affected assays, record on the request if the patient is being treated with NAC.
  • Monitor the MHRA website or subscribe to email alerts for any further FSNs on this issue.

Deadlines for actions

Actions underway: 28 June 2016

Actions complete: 22 August 2016

Device details

List of assays affected:

Assay Test code Catalogue number Siemens material number (SMN) Lot number
ADVIA chemistry products affected by N-acetylcysteine (NAC) only        
Lactate LAC 74051 10325776 All
Glucose oxidase,concentrated reagents GLUO_c 74721 10335872  
ADVIA chemistry products affected by N-acet** ylcysteine (NAC) and metamizole**        
Cholesterol_2 CHOL_2 74719 10376501 All
Cholesterol_c CHOL_c 74718 10335874  
Enzymatic creatinine_2 ECRE_2 74330 10335869  
Glucose oxidase GLUO 74020 10492319  
Triglycerides_2 TRIG_2 74082 10335892  
Triglycerides_2concentrated TRIG_c 74084 10697575  
Uric acid UA 74021 1030949210341133  
Uric acid, concentratedreagents UA_c 74715 10335873  
Fructosamine FRUC 74080 10361941  
Dimension products affected by N-acet** ylcysteine (NAC) and metamizole**        
Triglycerides TGL DF69A 10444906 All
Enzymatic creatinine EZCR DF270B 10444970  
Dimension Vista products affected by N-acet** ylcysteine (NAC) and metamizole**        
Triglycerides TRIG K2069 10445093 All
Enzymatic creatinine ECREA K1270A 10700444  

Note: Dimension® URCA and Dimension Vista® URCA are not Trinder reaction assays but they do produce peroxide and are susceptible to metamizole interference.


Siemens has issued Field Safety Notices regarding false low results on a number of assays carried out by their ADVIA Dimension/Dimension Vista instruments. This is due to the interference of NAC in affected assays that use the Trinder reaction. NAC is the accepted antidote for acetaminophen toxicity.

Patients being treated with metamizole/dipyrone/novaminsulfone are also affected but these products are not licensed for use in the UK. Metamizole is an anti-inflammatory anti-pyretic drug that is not licensed in some countries because of the potential for nephrotoxicity.

Investigations suggest that the peroxidase used in the Trinder reaction employed by affected assays leads to interference with NAC, causing falsely low recovery leading to misinterpretation of their physiological status. Similar assays from other manufacturers may also be affected by NAC interference and this is currently under investigation.

The manufacturer is updating the instructions for use for the ADVIA assays.

Authorised representative contacts

Siemens Healthcare Diagnostics Limited
Newton House, Sir William Siemens Square
Frimley, Camberley
GU16 8QD
Tel: 01908 282 433
Email: <>


If you are responsible for cascading these alerts in your organisation, these are our suggested distribution lists.

Trusts (NHS boards in Scotland)

CAS and SABS (NI) liaison officers for onward distribution to all relevant staff including:

  • A&E consultants
  • A&E departments
  • A&E directors
  • A&E nurses
  • Adult intensive care units
  • All wards
  • Anaesthesia, directors of
  • Anaesthetic medical staff
  • Anaesthetic nursing staff
  • Anaesthetists
  • Biochemists
  • Biomedical science departments
  • Chief pharmacists
  • Clinical governance leads
  • Clinical pathologists
  • Clinical pathology directors
  • Hospital pharmacies
  • Hospital pharmacists
  • Intensive care medical staff/paediatrics
  • Intensive care nursing staff (adult)
  • Intensive care nursing staff (paediatric)
  • Intensive care units
  • Intensive care, directors of
  • Medical directors
  • Paediatric intensive care units
  • Paediatric medicine, directors of
  • Pharmacists

Public Health England

Directors for onward distribution to:

  • Laboratory managers

Establishments registered with the Care Quality Commission (CQC) (England only)

  • Hospitals in the independent sector
  • Independent treatment centres
  • Private medical practitioners



Send enquiries about this notice to MHRA, quoting reference number MDA/2016/008 or 2016/004/001/601/011

Technical aspects

Salman Ghani, MHRA

Tel: 020 3080 6920


Clinical aspects

Mark Grumbridge, MHRA

Tel: 020 3080 7128


Reporting adverse incidents in England

Through Yellow Card

Northern Ireland

Alerts in Northern Ireland are distributed via the NI SABS system.

Enquiries and adverse incident reports in Northern Ireland should be addressed to:

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

Tel: 028 9052 3868

Fax: 028 9052 3900


Northern Ireland Adverse Incident Centre (NIAIC)

Please report directly to NIAIC using the forms on our website.


Enquiries and adverse incident reports in Scotland should be addressed to:

Incident Reporting and Investigation Centre,
Health Facilities Scotland,
NHS National Services Scotland

Tel: 0131 275 7575

Fax: 0131 314 0722


Reporting adverse incidents in Scotland

NHS Boards and Local Authorities in Scotland – report to Health Facilities Scotland.

Contractors such as private hospitals carrying out NHS work and private care homes that accept social work funded clients – report to Health Facilities Scotland.

Private facilities providing care to private clients report to the Care Inspectorate and MHRA.


Enquiries in Wales should be addressed to:

Healthcare Quality Division,
Welsh Government

Tel: 02920 823 624 / 02920 825 510


Reporting adverse incidents in Wales

Report to MHRA through Yellow Card and follow specific advice for reporting in Wales in MDA/2004/054 (Wales).

Download document

Siemens ADVIA Chemistry and Dimension/Dimension Vista products – risk of false low results due to interference with N-acetylcysteine (MDA/2016/008)

Help us improve GOV.UK

Don’t include personal or financial information like your National Insurance number or credit card details.