Sii

SII

SII stands for the systemic immune-inflammation index, a single-number measure derived from a routine complete blood count that summarizes aspects of inflammation and immune function. It is calculated using counts of certain immune cells and platelets to capture how much inflammation and immune activation are present. Clinically, a higher SII often signals greater inflammatory activity and can be associated with worse outcomes in a range of conditions, while a lower SII indicates a more balanced or controlled immune state. Doctors and researchers use SII to help stratify risk, monitor disease progression, and sometimes to guide treatment decisions alongside other information. The appeal of SII is that it is simple, low-cost, and available from commonly ordered blood tests. Still, SII should not be used by itself to make diagnoses because many factors, such as infections, medications, and other diseases, influence the value. It is most useful when tracked over time or combined with other clinical findings and tests. In short, SII is a convenient summary of immune and inflammatory status that supports clinical assessment and decision-making.