Assessment of renal function during high-dose methotrexate treatment in children with acute lymphoblastic leukemia.

Background: High-dose methotrexate (HD-MTX) is potentially nephrotoxic. The feasibility of novel biomarkers to indicate renal injury due to HD-MTX infusion was studied in children with acute lymphoblastic leukemia (ALL).

Procedure: Markers for glomerular and tubular injury were evaluated prospectively after HD-MTX infusion in 20 children with ALL. Plasma creatinine, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) were measured 24-48 hr before MTX-infusion and 24, 36, 48, and 72 hr after starting the HD-MTX treatment, and thereafter daily until the MTX concentration was below 0.1 µmol/L. Urine NGAL, β2 -microglobulin, and creatinine concentrations as well as dipstick and urinalysis were performed at the same time points.

Results: In children with ALL, HD-MTX treatment at 5 g/m(2) over 24 hr was well tolerated and none of the patients developed significant glomerular or tubular dysfunction. The mean plasma cystatin C level increased significantly (P < 0.001) from 0.83 mg/L at baseline to 0.94 mg/L at 36 hr after starting the HD-MTX treatment. The cystatin C concentration remained within reference range in all but two patients (10%). There was no significant change in plasma creatinine level during or after HD-MTX treatment, the values being normal in all patients. Plasma and urea NGAL did not increase during or after the HD-MTX treatment.

Conclusions: Our results suggest that plasma cystatin C concentration alone is a sensitive marker to monitor renal function during and after HD-MTX infusion in pediatric ALL patients. Plasma or urine NGAL do not provide any further advantage in the follow-up of these patients.