Background <p>Early identification of factors associated with renal allograft function remains important in kidney transplantation. Nutritional, inflammatory, and hemodynamic markers may provide complementary information on post-transplant recovery, but their prognostic value in living donor kidney transplantation remains unclear. We evaluated the associations of perioperative Prognostic Nutritional Index (PNI), Hemoglobin–Albumin–Lymphocyte–Platelet (HALP) score, Neutrophil-to-Lymphocyte Ratio (NLR), and Renal Resistive Index (RRI) with early and medium-term graft function after living donor kidney transplantation.</p> Methods <p>This retrospective single-center study included 74 adult living donor kidney transplant recipients transplanted between February 2024 and June 2025. NLR, PNI, and HALP were assessed preoperatively and on postoperative day 30 (POD30), and RRI was measured on postoperative day 1 (POD1). Graft function was evaluated by estimated glomerular filtration rate (eGFR) at POD30 and postoperative month 6 (POM6). Univariable and multivariable linear regression analyses were performed. Bootstrap resampling was used to assess the internal stability of parsimonious multivariable models, and ROC analysis was performed for POD30 PNI in relation to impaired POM6 graft function.</p> Results <p>At POD30, graft function was independently associated with recipient age, donor preoperative eGFR, and donor/recipient body surface area ratio, whereas POD1 RRI was not independently associated. At POM6, recipient age, donor preoperative eGFR, and POD30 PNI remained independently associated with graft function. Bootstrap resampling generally supported the stability of the main associations. POD30 PNI significantly discriminated impaired POM6 graft function, defined as eGFR &lt; 60 mL/min/1.73&#xa0;m² (AUC 0.725, 95% CI 0.598–0.851, <i>p</i> = 0.002), with an optimal cut-off of 53.0.</p> Conclusions <p>In living donor kidney transplantation, early graft function appears to be influenced mainly by recipient- and donor-related factors, whereas medium-term graft function is additionally associated with postoperative nutritional recovery reflected by POD30 PNI. PNI may provide complementary clinical information but should currently be regarded as an adjunctive monitoring marker rather than a stand-alone prognostic tool.</p> Trial registration <p>This study is a retrospective observational analysis and was not registered as a clinical trial since it does not involve any health care intervention on human participants.</p> Clinical trial number <p>Not applicable.</p>