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Interference of 7-hydroxymethotrexate with the determination of methotrexate in plasma samples from children with acute lymphoblastic leukemia employing routine clinical assays

Fotoohi, K; Skärby, Tor LU ; Soderhall, S; Peterson, C and Albertioni, F (2005) In Journal of Chromatography. B 817(2). p.139-144
Abstract
The accuracy of two clinical assays, the enzyme-multiplied immunoassay (EMIT) and fluorescence polarization immunoassay (FPIA2), universally employed for measurement of plasma levels of methotrexate (MTX) in children administered a high dose of this drug for treatment of acute lymphoblastic leukemia was evaluated here. Because of its superior specificity, sensitivity, and precision, high performance liquid chromatography (HPLC) was selected as the reference method with which the other two procedures were compared using approximately 420 different plasma samples for method comparison. 7-Hydroxymethotrexate (7-OHMTX), the major plasma metabolite of MTX, that can be detected in plasma at relatively high concentrations for long periods... (More)
The accuracy of two clinical assays, the enzyme-multiplied immunoassay (EMIT) and fluorescence polarization immunoassay (FPIA2), universally employed for measurement of plasma levels of methotrexate (MTX) in children administered a high dose of this drug for treatment of acute lymphoblastic leukemia was evaluated here. Because of its superior specificity, sensitivity, and precision, high performance liquid chromatography (HPLC) was selected as the reference method with which the other two procedures were compared using approximately 420 different plasma samples for method comparison. 7-Hydroxymethotrexate (7-OHMTX), the major plasma metabolite of MTX, that can be detected in plasma at relatively high concentrations for long periods following infusion of a high dose of MTX, was also quantitated by HPLC. Forty-two and 66 h after infusion, the plasma level of MTX was overestimated in 2% and 3% of the samples by the FPIA2 procedure in 5% and 31% by the EMIT assay. The overall correlation coefficients (r(2)) for the values obtained by FPIA2 or EMIT versus those based on HPLC were 0.989 and 0.663, respectively. The presence of 7-OHMTX exerted a highly significant influence (p = 0.0007 as determined by the unpaired t-test) on MTX measurement by the EMIT assay. We conclude that the rapid automated procedures routinely used at present and in particular EMIT, suffer from cross-reactivity with metabolites of MTX. Thus, the relatively high percentage of samples in which the level of MTX is overestimated at check-points by EMIT may result in longer periods of hospitalization, higher costs and prolonged administration of elevated doses of "rescue" leucovorin with an increased risk for relapse. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
chromatography, leukemia, high performance liquid, fluorescence polarization immunoassay, enzyme-multiplied immunoassay, methotrexate, 7-hydroxymethotrexate
in
Journal of Chromatography. B
volume
817
issue
2
pages
139 - 144
publisher
Elsevier
external identifiers
  • wos:000226957700001
  • pmid:15686977
  • scopus:15944390230
ISSN
1873-376X
DOI
10.1016/j.jchromb.2004.11.037
language
English
LU publication?
yes
id
6d311dfb-087a-4c4a-abe9-bee6a54b830a (old id 254433)
date added to LUP
2007-08-15 10:24:33
date last changed
2017-02-19 03:29:29
@article{6d311dfb-087a-4c4a-abe9-bee6a54b830a,
  abstract     = {The accuracy of two clinical assays, the enzyme-multiplied immunoassay (EMIT) and fluorescence polarization immunoassay (FPIA2), universally employed for measurement of plasma levels of methotrexate (MTX) in children administered a high dose of this drug for treatment of acute lymphoblastic leukemia was evaluated here. Because of its superior specificity, sensitivity, and precision, high performance liquid chromatography (HPLC) was selected as the reference method with which the other two procedures were compared using approximately 420 different plasma samples for method comparison. 7-Hydroxymethotrexate (7-OHMTX), the major plasma metabolite of MTX, that can be detected in plasma at relatively high concentrations for long periods following infusion of a high dose of MTX, was also quantitated by HPLC. Forty-two and 66 h after infusion, the plasma level of MTX was overestimated in 2% and 3% of the samples by the FPIA2 procedure in 5% and 31% by the EMIT assay. The overall correlation coefficients (r(2)) for the values obtained by FPIA2 or EMIT versus those based on HPLC were 0.989 and 0.663, respectively. The presence of 7-OHMTX exerted a highly significant influence (p = 0.0007 as determined by the unpaired t-test) on MTX measurement by the EMIT assay. We conclude that the rapid automated procedures routinely used at present and in particular EMIT, suffer from cross-reactivity with metabolites of MTX. Thus, the relatively high percentage of samples in which the level of MTX is overestimated at check-points by EMIT may result in longer periods of hospitalization, higher costs and prolonged administration of elevated doses of "rescue" leucovorin with an increased risk for relapse.},
  author       = {Fotoohi, K and Skärby, Tor and Soderhall, S and Peterson, C and Albertioni, F},
  issn         = {1873-376X},
  keyword      = {chromatography,leukemia,high performance liquid,fluorescence polarization immunoassay,enzyme-multiplied immunoassay,methotrexate,7-hydroxymethotrexate},
  language     = {eng},
  number       = {2},
  pages        = {139--144},
  publisher    = {Elsevier},
  series       = {Journal of Chromatography. B},
  title        = {Interference of 7-hydroxymethotrexate with the determination of methotrexate in plasma samples from children with acute lymphoblastic leukemia employing routine clinical assays},
  url          = {http://dx.doi.org/10.1016/j.jchromb.2004.11.037},
  volume       = {817},
  year         = {2005},
}