# Early Post-Transplant Protein Biomarkers for Risk Stratification of Renal Allograft Dysfunction: Diagnostic Value and Clinical Chemistry Perspectives

## TL;DR

This study shows that the protein KIM-1 can detect early kidney transplant problems better than traditional tests like serum creatinine.

## Contribution

The study identifies KIM-1 as a novel early biomarker for predicting long-term kidney transplant outcomes.

## Key findings

- KIM-1 levels were significantly higher in transplant patients compared to healthy controls.
- KIM-1 outperformed serum creatinine in predicting future graft dysfunction.
- Higher KIM-1 levels correlated with more severe early tubular injury in high-risk patients.

## Abstract

Background: Early recognition of renal allograft dysfunction requires biochemical markers capable of detecting molecular injury before functional decline becomes apparent. Serum creatinine, a late and nonspecific indicator of renal function, has limited value for early diagnosis. Protein biomarkers implicated in tubular injury, inflammation, and immune activation—including neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), β2-microglobulin, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α)—have emerged as promising alternatives. This study evaluated early post-transplant serum profiles of these biomarkers and their prognostic relevance for long-term graft outcomes. Methods: Nineteen adult recipients undergoing primary kidney transplantation were prospectively enrolled. Serum creatinine and protein biomarkers were measured 24 h post-transplant using validated immunochemical assays. Biomarker concentrations were compared with values from healthy controls, and correlations with renal function at 12 months were assessed. Receiver operating characteristic (ROC) analysis was used to evaluate predictive performance. Results: Significant biochemical alterations were observed at 24 h post-transplant. KIM-1 levels were markedly elevated compared with controls (74.50 ± 98.45 vs. 10.54 ± 17.19 ng/mL; p = 0.01), consistent with early tubular injury. IL-1β and NGAL showed upward trends without reaching statistical significance. β2-microglobulin and TNF-α levels did not differ substantially from control values. Serum KIM-1 correlated with serum creatinine both at 24 h (r = 0.35) and at 12 months (r = 0.40). ROC analysis identified a KIM-1 threshold of 24.5 ng/mL (AUC = 0.68) as a potential indicator of future graft dysfunction, outperforming serum creatinine (AUC = 0.64). Six patients experienced graft dysfunction at 12 months post-transplant, five of whom had serum creatinine values > 5 mg/dL at 24 h. Based on early creatinine levels, patients were stratified into low-risk (creatinine < 5 mg/dL; n = 10) and high-risk groups (creatinine > 5 mg/dL; n = 9). Mean KIM-1 concentrations were significantly higher in the high-risk group (110.68 ± 115.29 vs. 26.67 ± 18.05 ng/mL; p = 0.05), consistent with more severe early tubular injury. Conclusions: Among the evaluated biomarkers, KIM-1 demonstrated the strongest potential as an early biochemical indicator of renal allograft dysfunction. Its rapid post-transplant elevation underscores its sensitivity to early tubular injury. Further prospective validation in larger, multicenter cohorts is warranted.