Impact of High Serum Lysozyme Activity on Renal Function and Survival Outcomes in Transplant-Eligible and Ineligible Acute Myeloid Leukemia.

Lysozyme-induced nephropathy is a complication of chronic myelomonocytic leukemia and acute myeloid leukemia (AML). Few studies have discussed the association between blood lysozyme levels at AML onset and AML prognosis, which this study aimed to address. A total of 166 AML patients (72 transplant-eligible and 94 transplant-ineligible cases) undergoing chemotherapy at our hospital with recorded serum lysozyme levels were retrospectively included between March 2012 and March 2024. The median age, creatinine, and serum lysozyme at diagnosis were 65 (22-86) years, 0.85 mg/dL (0.43-3.56), and 16.4 μg/mL (0.3-560.0), respectively. Hematopoietic stem cell transplantation was performed in 43.4% of all patients. At initial diagnosis, the lysozyme and creatinine levels were positively correlated (the Spearman rank correlation coefficient: +0.516, p < 0.05). Using ROC analysis, the optimal serum lysozyme cutoff values for predicting AKI (KDIGO > 0) at AML onset were determined to be 22.4 μg/mL (AUC, 0.89: 95% CI: 0.847-0.951). The two-year overall survival (OS) did not differ significantly between patients with lysozyme < 22.4 μg/mL and patients with lysozyme ≥ 22.4 μg/mL (two-year OS, 39.5% vs. 42.2% [95% CI, 29.2%-49.6% vs. 29.8%-54.1%]; p = 0.862). The same trend was observed in the transplantation group. After remission induction, most patients with high-lysozyme levels showed creatinine level recovery (AML onset: median 1.15 mg/dL, 1 month later: median 0.72 mg/dL, 3 months later: median 0.65 mg/dL). The effect of lysozyme levels on prognosis is limited because renal function recovers in many patients with high-lysozyme levels after chemotherapy.