Diagnostic values ​​of biochemical and hematological parameters and radiological imaging in the early diagnosis of acute kidney injury in patients with sepsis and septic shock

Objective: In patients with sepsis and septic shock, we aimed to investigate the effectiveness of urinary neutrophil gelatinase-associated lipocalin (uNGAL), Renal Resistive Index (RRI) measured by Doppler ultrasonography (USG), hemogram parameters (neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, platelet/lymphocyte ratio, and platelet count), and biochemical markers in the early diagnosis of sepsis-associated acute kidney injury (AKI). Materials and Methods: A total of 123 patients diagnosed with sepsis or septic shock (SOFA>2) and followed in the intensive care unit or wards were included in the study. Following the diagnosis of sepsis, hemogram (NLR, MLR, PLR), biochemical analyses, and sterile urine samples were obtained on day 1 (within 0–6 hours), day 2, and day 3. NGAL levels in urine samples were measured using the ELISA method. In parallel, renal Doppler USG was performed on three consecutive days to measure RRI. Patients with AKI were identified using the RIFLE criteria. Those requiring renal replacement therapy (RRT) or who died during follow-up were excluded. Data were analyzed using IBM SPSS 25.0 (SPSS Inc., Chicago, IL, USA). Results: According to KDIGO criteria, AKI developed in 39.8% of patients on day 1, 43.9% on day 2, and 48.8% on day 3. RRI was found to be a statistically significant (p <0.001) and reliable parameter. ROC curve analysis was performed to assess the reliability of RRI on each of the three days, and new cutoff points were determined using the Youden Index, confirming the high predictive value of RRI for AKI. uNGAL was not identified as a supportive parameter for early AKI diagnosis. Among hemogram parameters, thrombocytopenia was significantly associated with kidney injury (p < 0.05), while PLR and MLR were not statistically significant (p > 0.05). NLR was significant only on day 2 but not on other days, and thus was not considered a supportive parameter. Regarding mortality, hemogram parameters were not statistically significant (p > 0.05), 4 while LDH/albumin and lactate/albumin ratios were identified as statistically significant and strong predictors (p < 0.001). Conclusion: Our study demonstrated that RRI measurements can be used in the early period (first three days) to detect AKI in patients with sepsis, whereas uNGAL was insufficient for predicting AKI. As the stage of AKI progressed, platelet counts decreased, suggesting that thrombocytopenia may serve as a predictive marker. NLR, MLR, PLR, lactate/albumin, and LDH/albumin ratios were not found to be reliable parameters for early AKI diagnosis. However, for predicting 28-day mortality, lactate/albumin and LDH/albumin ratios were valuable predictors, whereas hemogram parameters were not.