Role of cystatin C in predicting the risk of hypermethotrexemia and kidney injury after high-dose methotrexate chemotherapy in childhood acute lymphoblastic leukemia.

This study analyzed the correlation among serum cystatin C (CysC) levels, hypermethotrexemia, and kidney damage following high-dose methotrexate (HD-MTX) chemotherapy in children with acute lymphoblastic leukemia (ALL) to aid early prediction, diagnosis, and treatment. Clinical data from 103 children diagnosed with ALL were collected, totaling 412 HD-MTX chemotherapy sessions. The association between 20-h serum CysC levels, 44-h MTX blood concentrations, and 44-h serum creatinine levels was analyzed. Forty-four patients in the low-risk group received 3 g/m2 of HD-MTX, while 59 patients in the intermediate-risk group received 5 g/m2 of HD-MTX. Some patients experienced a 20% dose reduction due to high 44-h MTX concentrations in previous cycles; however, no dose increases were observed. In the high MTX concentration group, 31.4% (27/86) of patients had elevated 20-h serum CysC levels, significantly higher than the 2.8% (9/324) in the low-concentration group (P < 0.001). However, baseline serum CysC levels did not differ significantly (P = 0.377). Among the 36 cycles with elevated 20-h serum CysC levels, 19.4% (7/36) of patients progressed to elevated serum creatinine levels at 44 h. In contrast, only one patient in the normal serum CysC group showed such progression (P < 0.001). Furthermore, the 20-h serum CysC levels positively correlated with 44-h MTX concentrations and serum creatinine levels. Our findings indicate that 20-h serum CysC levels can predict hyperammonemia and kidney injury.