Platelet-to-WBC ratio

The platelet-to-WBC ratio helps assess systemic inflammation, infection severity, and bone marrow function. A low ratio may indicate severe infection (WBCs elevated, platelets consumed), inflammatory conditions, or hematologic malignancies where WBC production is abnormally high. An elevated ratio can suggest reactive thrombocytosis, recovery from infection, or certain myeloproliferative disorders. The ratio is particularly useful for predicting outcomes in sepsis, assessing cardiovascular risk (as both components influence thrombosis and inflammation), and monitoring treatment response in infections or inflammatory conditions.

Changes in the ratio over time often provide earlier warning of clinical deterioration or improvement than individual cell counts alone.