BACKGROUND: Doubling of serum creatinine (DSC) in transplantation has been seen as the end-point of renal function without pathological evidence. We conducted this study to elucidate the relationship between DSC and pathological findings.

MATERIAL AND METHODS: We conducted a retrospective cohort study to illustrate pathologic changes in patients receiving a kidney biopsy in the previous 5 years with clinicopathological correlations to DSC and proteinuria.

RESULTS: Of a total of 99 kidney recipients (146 biopsies), results of graft biopsy were as follows: calcineurin inhibitor toxicity (CNI) (38.7%) and rejection (36.9%). Compared to males, females had higher proportions of class I (p=0.003) and class II PRA (p<0.001), and a higher rejection rate (p=0.042), but had the same clinical outcomes as males, like eGFR at follow-up (p=0.882), DSC (p=0.703), and proteinuria (p=0.745).                         Pathological diagnoses and findings were related to proteinuria: glomerulopathy (HR=4.9, p=0.01), AMR (HR=2.5, p=0.025), especially acute AMR (HR=2.9, p=0.008), chronic glomerular change (HR=10.2, p=0.002), arteriolar hyaline (HR=2.3, p=0.026), and mesangial matrix change (HR=6.3, p=0.002).                         BK nephropathy and rejection were the only 2 risk factors. Pathological findings favoring AMR (PTC infiltration and glomerulitis) showed a greater risk of DSC compared with those favoring CMR (interstitial inflammation, intimal arteritis, and tubulitis). DSC was correlated with clinical manifestation (rejection) and provided strong pathological evidence.

CONCLUSIONS: There was more acute rejection and chronic pathological change in women, but outcomes were the same due to less activity of renin-angiotensin-aldosterone and hyperfiltration in females. DSC as an end-point of graft function can be used to identify recipients, especially AMR or mixed AMR and CMR. 1. All forms of support received by each author: None of the authors received support. 2. Any potential conflict of interest for each author: No conflict of interest for any of the authors.

Keywords: Recipient, graft biopsy, doubling of serum creatinine, renal transplantation