Works well on Abbott Architect as well. We switched to Ark assay as wel.

Bart Ballieux
Leiden University Medical Centre
Netherlands 

-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Iqbal, Jhangir
Sent: dinsdag 22 mei 2012 13:24
To: [log in to unmask]
Subject: Re: Methotrexate assay

Works well on Beckman Coulter DXC800 analyser

LoQ 0.04 umol/l reproducible

Very good comparison between Abbott TDx methotrexate and Ark methotrexate, has been in routine use for 8 months.


Best wishes
Jhangir
 
Mr Jhangir Iqbal
Principal Clinical Biochemist
The Royal Marsden NHS Foundation Trust
Biochemistry Department
Sutton, Surrey
 
Tel: 020 8661 3207
 

-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Ivison Fiona (RW3) CMFT Manchester
Sent: 22 May 2012 12:13
To: [log in to unmask]
Subject: Re: Methotrexate assay

I can share some data/information on this assay which we have been running routinely for at least 6 months on Cobas 6000 instruments.



Fiona



Dr Fiona Ivison
Principal Biochemist
Central Manchester Foundation Trust
Oxford Rd
manchester
M13 9WL

0161 701 1203
07806 883960
________________________________
From: Clinical biochemistry discussion list [[log in to unmask]] on behalf of [log in to unmask] [[log in to unmask]]
Sent: 22 May 2012 11:43
To: [log in to unmask]
Subject: Vb: Re: Methotrexate assay


Has anyone evaluated the Ark-Methotrexate with claimed LoQ 0,04 umol/L? On what platform? Experiences?

http://www.ark-tdm.com/DB_methotrexate.html

Regards
Goran Brattsand, MD, Ph D
Clinical chemistry
NUS
S-901 85 Umea
Sweden

----- Vidarebefordrat av Göran Brattsand/US/VLL/SE   2012-05-22 12:30 -----
Från:   "Miller,James J." <[log in to unmask]>
Till:   [log in to unmask]
Datum:  2012-05-21 17:15
Ärende:         Re: Methotrexate assay

________________________________



Mohammed El Sammak asked about more sensitive methotrexate assays since the discontinuation of the TDx.   Saeed Jortani and colleagues just published a modification of the Siemens Viva E methotrexate assay to improve the low end sensitivity.  The citation and abstract are below.  -Jim


Therapeutic Drug Monitoring
Issue: Volume 34(2), April 2012, p 193–197
Copyright: © 2012 Lippincott Williams & Wilkins, Inc.
Publication Type: [Original Article]
DOI: 10.1097/FTD.0b013e31824b93a5
ISSN: 0163-4356
Accession: 00007691-201204000-00014
Keywords: methotrexate, EMIT, sensitivity

Improved Sensitivity for Methotrexate Analysis Using Enzyme Multiplied Immunoassay Technique on the Siemens Viva-E Instrument Borgman, Mark P. PhD*; Hiemer, Mary F. MT(ASCP)*; Molinelli, Alejandro R. PhD†; Ritchie, James C. PhD‡; Jortani, Saeed A. PhD* Author Information *Department of Pathology and Laboratory Medicine, University of Louisville School of Medicine, Louisville, Kentucky †Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, Tennessee ‡Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia.

The authors declare no conflicts of interest.

Correspondence: Saeed A. Jortani, PhD, Department of Pathology and Laboratory Medicine University of Louisville School of Medicine, 511 South Floyd Street, Room 227 Louisville, KY 40202 (e-mail: [log in to unmask]).
Received September 8, 2011
Accepted January 17, 2012

Abstract
Background: The available assay kit for methotrexate (MTX) using the Syva enzyme multiplied immunoassay technique (EMIT) reagents on the Siemens Viva-E instrument allows for the detection of MTX in serum or plasma to concentrations as low as 0.3 µmole/L. Current clinical decision points for MTX therapeutic drug monitoring and leucorvorin rescue exist at concentrations below that limit.
Objective: The goal of this study was to lower the limit of MTX quantitation to 0.05 µmole/L using the EMIT assay technology.
Methods: EMIT MTX assay parameters were modified on the Viva-E instrument to increase the sample volume, alter the calibration method, and employ an alternate calibrator set created to achieve lower detection. Intraassay and interassay precision was assessed for MTX controls.
Results: We observed a CV of 9.4% for intraassay precision with a bias of <0.01% and a CV of 15.7% for interassay precision with a bias of 22.5% for the 0.05 µmole/L control. Precision data for all other controls were <4%. The modified EMIT MTX assay and the unmodified approved assay were compared with a high sensitivity fluorescence polarization immunoassay method. Linear regression of correlation data revealed that both the modified and the commercial EMIT assays produced positive bias compared with the high sensitivity fluorescence polarization immunoassay method (y-int = 0.03 and 0.08, respectively). However, the modified EMIT assay had the best correlation in the low range (0.03–2 µmole/L). Additionally, endogenous and chemical interference testing demonstrated that the modified assay was not affected to a clinically significant extent.
Conclusions: The described modifications have enhanced the sensitivity of the Syva EMIT assay for MTX measurements down to 0.05 µmole/L with acceptable precision that can be used in clinical practice for monitoring MTX therapy.

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