OBJECTIVETo study blood concentrations of methotrexate (MTX) in Uyghur and Han children with acute lymphoblastic leukemia (ALL), and to provide criteria for judging the incidence of adverse effects of MTX.

METHODSTwenty-eight children with ALL (15 Han children and 13 Uyghur children), who received high-dose MTX chemotherapy, were divided into >10 μmol/L and ≤10 μmol/L groups according to 24-hour blood concentration of MTX, and divided into >1.0 μmol/L and ≤1.0 μmol/L groups according to 48-hour blood concentration of MTX. Enzyme multiplied immunoassay was used to measure blood concentrations of MTX in the MTX-treated children at 24 and 48 hours after MTX administration, and the adverse effects were observed.

RESULTSThere was no significant difference in the incidence of adverse effects between the >10 μmol/L and ≤10 μmol/L groups (P>0.05). The >1.0 μmol/L group showed higher incidences of gastrointestinal reactions and mucosal injuries than the ≤1.0 μmol/L group (P<0.05), but no significant difference was found between the two groups with respect to the incidence of abnormal liver function and bone marrow suppression (P>0.05). Compared with Uyghur children, Han children showed higher 24- and 48-hour blood concentrations of MTX (P<0.05) and higher incidence of abnormal liver function, mucosal injuries, and bone marrow suppression (P<0.05).

CONCLUSIONSThe 24-hour blood concentration of MTX cannot be used to predict the incidence of adverse effects in MTX chemotherapy, but 48-hour blood concentration of MTX is helpful in this regard. There are significant differences in 24- and 48-hour blood concentrations of MTX and the incidence of adverse effects between Uyghur and the Han children with ALL who receive MTX chemotherapy. Monitoring of blood MTX concentration maybe significant for timely adjustment of MTX dosage and individualized MTX chemotherapy.