Early Hemoglobin Trajectories as Predictors of Initial Graft Function in Kidney Transplant Recipients

Background Early detection of suboptimal kidney allograft recovery is clinically important, yet conventional markers such as creatinine often lag. Prior studies mostly assessed post-transplant anemia at later time points and did not examine daily hemoglobin (Hb) dynamics during the first postoperative week. Methods We retrospectively analyzed 859 adult kidney transplant recipients (Khorshid Hospital, Iran, 2011–2025). Exclusions included abnormal iron status, parathyroid disorders, active bleeding, baseline rejection, post-transplant dialysis, or erythropoietin/transfusion. Daily Hb, serum creatinine (Cr), and estimated glomerular filtration rate(eGFR) (CKD‑EPI 2021, race‑free) were recorded for post-operative day (POD)1–7. Hb slope (g/dL/day) was calculated via linear regression, and patients were classified as Hb Risers (slope > 0) or Non-Risers. Primary endpoint was eGFR at POD7. Analyses included repeated-measures, Pearson correlations, multivariable regression (adjusted for age, sex, baseline Cr, immunosuppressants), and mixed-effects models for Cr trajectories. Results Mean Hb declined until POD3 and recovered by POD6–7; Cr fell and eGFR rose correspondingly. Hb Risers (57.9%) had faster Cr recovery and higher eGFR at POD7. In adjusted regression, Hb slope independently predicted eGFR_day7 (+ 23.1 mL/min/1.73 m² per 1 g/dL/day; 95% CI 17.0–29.2; p < 0.001). Mixed-effects models confirmed faster renal recovery in Risers. Conclusions Early, daily Hb trajectories during the first postoperative week closely parallel renal recovery. Hb slope provides complementary, independent information beyond baseline creatinine, highlighting its potential as a practical early indicator of graft function. Prospective multicenter validation and mechanistic studies are warranted.