Abstract
Introduction: Methotrexate (MTX) is the most generally administered antimetabolite
in pediatric cancers. Renal excretion is the major route of elimination of MTX. However,
renal toxicity and delayed MTX elimination is a particular concern and direct serum MTX
concentration is a gold standard for renal toxicity monitoring. However, checking plasma
MTX concentrations in most oncology institutions is not always possible especially in less
developed countries.
Objectives: The purpose of this study was to further assess the renal function after
administration of high-dose MTX by parameters such as serum creatinine and Cr clearance
rate.
Patients and Methods: This is a cross-sectional descriptive analytic study. The study was
conducted on children with acute lymphoblastic leukemia, non-Hodgkin lymphoma and
osteosarcoma receiving high doses MTX. Patients’ age was ranged from 5 to 16 years. Serum
MTX concentration and serum Cr were measured at 24, 48 and 96 hours after receiving MTX
and then Cr clearance calculated based on available formulas. All the statistical analyses were
done by SPSS 20.0 statistical software
Results: This study was performed on 4 patients with osteosarcoma, 3 patients with leukemia
and one patient with lymphoma. MTX concentration reduced significantly during 96 hours
(P<0.001). A significant correlation between Cr clearance at 48 hours and the average of
serum MTX concentration (P=0.001) were observed. Furthermore there were significant
correlations between Cr at 24 hours (P=0.003), 48 hours (P=0.009) and 96 hours (P=0.044),
with the average of serum MTX concentration.
Conclusion: Our findings indicated that serum Cr and Cr clearance can be used to estimate
the average of serum MTX concentrations.