The aim of this study is to investigate, in patients admitted to the intensive care unit either for reasons other than sepsis who subsequently develop sepsis or with a primary diagnosis of sepsis, whether monocyte distribution, monocyte-to-lymphocyte ratio, and neutrophil-to-lymphocyte ratio can be used in addition to conventional biomarkers, and to examine their relationships with these biomarkers.

For Group I (control group) patients, WBC, NLR, MLR, and monocyte distribution(MD) parameters obtained from the complete blood count on the day of their anesthesia outpatient clinic visit were used in the study. For Group II and Group III patients, on the day of sepsis diagnosis, lactate, CRP, PCT, WBC, NLR, MLR, and monocyte distribution(MD) values were recorded. For Groups II and III, SOFA and APACHE-II scores were calculated within the first 24 hours and documented. The day of sepsis diagnosis was defined as T0, and subsequent measurements of lactate, CRP, PCT, WBC, NLR, MLR, and monocyte distribution(MD) were recorded every 48 hours until sepsis resolution, discharge, or death, as T1, T2, T3, and T4, respectively. The monocyte distribution parameter is a research parameter within the complete blood count and does not have a defined reference laboratory range. In our study, statistical analysis of monocyte distribution(MD), MLR and NLR values from the control group was performed to determine a cut-off value.

Inclusion Criteria:

• Patients monitored in the intensive care unit for at least 24 hours
• Age over 18 years
• Diagnosis of sepsis or septic shock

Exclusion Criteria:

• Patients with hematological diseases
• Patients who have undergone organ or bone marrow transplantation
• Patients diagnosed with AIDS
• Patients receiving immunosuppressive therapy for any reason
• Patients with chronic renal failure
• Patients with liver failure not related to sepsis
• Patients admitted due to intoxication
• Patients with intracranial pathologies (e.g., mass, hemorrhage) that may lead to morbidity due to volume loading

The study population consists of three groups: Group I: Control group - patients over 18 years of age, classified as ASA I-II, with no infection, who applied to the anesthesia outpatient clinic and did not meet any exclusion criteria; Group II: patients who were admitted to the intensive care unit for reasons other than sepsis and subsequently developed sepsis; Group III: patients admitted to the intensive care unit with a primary diagnosis of sepsis.