Complete Blood Count in Delayed Graft Function: A Narrative Review.

Delayed graft function (DGF) is a common and critical complication following kidney transplantation, marked by acute kidney injury necessitating dialysis within the first postoperative week. Early detection of patients at risk is crucial for optimizing perioperative management and enhancing graft outcomes. While novel biomarkers have been suggested, their clinical application remains limited. This review explores the potential of complete blood count (CBC) parameters and derived indices as cost-effective, accessible alternatives. This narrative review synthesizes findings from studies examining the relationship between CBC parameters - such as hemoglobin, white blood cell count, and platelet count, and hematological indices like neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) - and DGF risk in kidney transplantation. A comprehensive literature search was conducted across major biomedical databases using targeted keywords. Selected studies were analyzed to assess the predictive value, underlying mechanisms, and clinical utility of these parameters. This review highlights a significant association between specific CBC parameters and DGF risk. Notably, low pre- or perioperative hemoglobin levels, significant perioperative hemoglobin drops, elevated pre- or post-transplant NLR, and altered PLR are correlated with increased DGF risk. These associations are thought to reflect underlying pathophysiological mechanisms, including inflammatory responses, ischemia-reperfusion injury, and immune cell activation. However, variability in study design, sampling time points, donor types, and DGF definitions complicates interpretation, underscoring the need for prospective multicenter validation. CBC-derived parameters demonstrate promising associations with DGF risk, particularly low pre-transplant hemoglobin levels and perioperative declines >1.3 g/dL. Preoperative NLR >3.5 and postoperative leukocyte ratios may aid in early graft dysfunction detection. Despite inconsistent evidence for platelet-related indices, further prospective multicenter studies are essential to confirm clinical utility and establish standardized cutoff values.