Determination of Methotrexate in Serum by a Rapid, Fully Mechanized Enzyme Immunoassay (EMIT)

Abstract

Summary: A homogeneous enzyme immunoassay for the determination of methotrexate in serum (EMIT, Syva Corp.) was fully mechanized by the use of an Eppendorf analyzer 5010. Coefficients of variation from day to day were in the range 2-16%. A comparison of the results obtained by EMIT and a radioimmunoassay (Methotrexate 125 I Radioimmunoassay Kit, Diagnostic Biochemistry Inc.) in a series of 50 samples from patients showed a good correlation between both methods. The specificity of the EMIT assay appeared to be adequate. The time required for the determination of about 20 patient samples by this procedure was only about 80 minutes. From our clinical experience the EMIT assay appears to be well suited for routine monitoring of methotrexate serum concentrations above 0.1 μπιοΐ/l during intrathecal and high dose methotrexate therapy. Bestimmung von Methotrexat im Serum mit einem rasch durchf hrbaren, vollmechanisierten Enzymimmunotest (EMIT)Zusammenfassung

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

“…Furthermore several endogenous and exogenous substances have been widely reported to interfere with the EMIT assay. For instance, Oellerich et al [13] reported that bilirubin, hemoglobin and triglycerides influence the EMIT assay in such a manner as to cause deviations of less than 10% from the expected MTX values.…”

Establishing Syva Methotrexate Assay on Siemens Dimension RxL Analyzer: Experience in a Tertiary Cancer Care Laboratory

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Th1 and Th2 cytokines exert regulatory effects upon islet microvascular areas in the NOD mouse

“…Results are given as units per milligram (U/mg) of protein (means of triplicates with an intra‐assay variation coefficient of 2.7%). The detection limit was found to be 2 U/mg protein [Oellerich et al, 1980]. The concentration of proteins was determined by Lowry's method [Lowry et al, 1951].…”