A combined score from your blood count that reflects your body’s overall inflammation and immune balance.
The systemic immune-inflammation index (SII) is a calculated value, not a separate blood test. It combines three figures from a full blood count: platelets, neutrophils and lymphocytes.
The formula is: SII = (platelet count × neutrophil count) ÷ lymphocyte count.
By combining three cell types that all shift during inflammation and immune stress, SII aims to give a fuller picture of systemic inflammation than any single ratio. It has been studied as a prognostic marker across cancer, cardiovascular disease and other conditions.
A higher SII reflects a more inflammatory, immune-stressed state and has been linked with poorer outcomes in several settings. A lower value is generally more favourable.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
There is no firmly established healthy reference range for SII, and values vary widely by population and assay. It is used mainly as a relative prognostic marker, where higher values track with more inflammation and worse outcomes. Interpret as a trend with a clinician rather than against a fixed cutoff.
All three components shift with infection, stress, exercise, corticosteroids and time of day, so recent illness can move the index. SII is non-specific and rises with many conditions, so it is best read in context and as a trend.
Read with its components, platelet, neutrophil and lymphocyte counts, and alongside the neutrophil to lymphocyte ratio and hs-CRP.
What does a high or low SII mean? High values may point to more inflammation or immune stress. Low values may reflect a lower inflammatory burden. Your symptoms and other labs provide context.
Do I need to fast for this test? No. Fasting is not required for SII or a standard complete blood count.
What can affect my result? Recent illness, vaccines, hard workouts, dehydration, pregnancy, smoking, alcohol, and medicines like steroids or chemotherapy can shift counts.
How often should I test? Timing depends on your care plan. Many people recheck during treatment follow-ups or after symptoms change.
How long do results take? Results are usually ready in about 7 days.
What should I discuss with my clinician? Review trends, recent illnesses, and all medications or supplements. Ask how SII fits with CRP and your complete blood count.
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