Delayed Elimination Concentrations of High-Dose Methotrexate in Adults With Hematological Malignancies: To Standardize or Not? A Scoping Review

Significant variability exists in the thresholds used to define delayed HDMTX elimination, particularly at 48 hours, with the differences not explained by assay method. These inconsistencies affect clinical decisions, including toxicity predictions and rescue therapy implementation. Although standardization is needed to improve comparability, threshold definitions should also reflect population-specific pharmacokinetics and toxicity profiles to support more precise HDMTX monitoring and outcomes.