A rapid enzymatic assay for methotrexate in serum.
A kinetic enzymological assay for methotrexate in serum is described; the results are available after 1.5 hours. The lower limit of sensivity is 50 nmol/1; the day-to-day variation coefficients compare favourably with other procedures (about 7% in the 200-600 nmol/1 range). The method uses purified dihydrofolic acid reductase from bovine liver. The problem of its instability in the  assay is circumvented by several measures, e.g. the use of a reaction rate analyser.
D006801:Humans; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008722:Methods; D008727:Methotrexate / Q000097:blood* / Q000134:cerebrospinal fluid; D013762:Tetrahydrofolate Dehydrogenase
D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate