The Need for Standardized Guidelines for the Use of Monocyte Distribution Width (MDW) in the Early Diagnosis of Sepsis.

Sepsis is a complex and potentially life-threatening syndrome characterized by an abnormal immune response to an infection, which can lead to organ dysfunction, septic shock, and death. Early diagnosis is crucial to improving prognosis and reducing hospital management costs. This narrative review aims to summarize and evaluate the current literature on the role of monocyte distribution width (MDW) as a diagnostic biomarker for sepsis, highlighting its advantages, limitations, and potential clinical applications. MDW measures the volumetric distribution width of monocytes, reflecting monocytic anisocytosis, and is detected using advanced hematological analyzers. In 2019, it was approved by the FDA as a biomarker for sepsis due to its ability to identify systemic inflammatory response at an early stage. Thirty-one studies analyzed by us have shown that an increased MDW value is associated with a higher risk of sepsis and that its combination with clinical parameters (such as qSOFA) and other biomarkers (CRP, PCT) can enhance diagnostic sensitivity and risk stratification capacity. Despite its high sensitivity, MDW has lower specificity compared to more established biomarkers such as procalcitonin, thus requiring a multimodal integration for an accurate diagnosis. The use of MDW in emergency and intensive care settings represents an opportunity to improve early sepsis diagnosis and critical patient management, particularly when combined with other markers and clinical tools. However, further studies are needed to define a universal cut-off and confirm its validity in different clinical contexts and pathological scenarios.