Correlation analysis of cyclosporine A trough concentration with hematological and biochemical parameters: a retrospective study in pediatric aplastic anemia.

Aplastic anemia (AA) is a life-threatening pediatric hematological disorder requiring immunosuppressive therapy with cyclosporine A (CsA), which has a narrow therapeutic window and significant interindividual variability. The relationship between CsA trough concentration and routine laboratory markers in children remains poorly defined. This retrospective study enrolled 14 pediatric AA patients (70 paired samples) followed over 12 months. Associations between CsA trough concentration and hematological, hepatic, and renal parameters were analyzed using linear mixed-effects models with random intercepts to account for repeated measures, complemented by time-stratified Pearson correlations. Benjamini-Hochberg false discovery rate (FDR) correction was applied for multiple comparisons. CsA trough concentration showed a significant positive association with blood urea nitrogen (β = 0.012, 95% CI: 0.007-0.017, P < 0.001, FDR q = 0.002), with the strongest correlations during the first three months (r = 0.686-0.914). Serum creatinine, platelet count, and aspartate aminotransferase showed isolated time-point correlations, while no significant associations were observed for other hematological or hepatic parameters after FDR correction. This exploratory study identifies a consistent, time-dependent association between CsA trough concentration and BUN in pediatric AA, suggestive of early hemodynamic effects rather than cumulative nephrotoxicity. The lack of correlation with hematological parameters highlights the multifactorial nature of hematopoietic recovery. These findings provide a foundation for prospective studies to refine personalized CsA dosing strategies.