Associations between systemic immune-inflammation index and iron deficiency.

Area of Science:

• Hematology
• Immunology
• Nutritional Science

Background:

• The systemic immune-inflammation index (SII) is a recognized biomarker for disease progression and treatment outcomes.
• The role of SII in iron deficiency (ID) and related conditions remains largely unexplored.
• Understanding the association between systemic inflammation and iron metabolism is crucial for public health.

Purpose of the Study:

• To investigate the association between the systemic immune-inflammation index (SII) and iron deficiency (ID) in U.S. adults aged 20-80.
• To explore the relationship between SII and various iron metabolism indicators.
• To compare the association of SII with ID versus C-reactive protein (CRP).

Main Methods:

• Cross-sectional analysis of 4,075 participants from the National Health and Nutrition Examination Survey (NHANES).
• Assessment of SII (platelet counts × neutrophil counts/ lymphocyte counts) and iron indicators (TBI, SF, sTfR, TIBC, TS, MCV, Hb).
• Multiple linear and logistic regression models were used to analyze associations, with interaction tests for age, sex, and race.

Main Results:

• Individuals with high SII showed lower levels of SF, TBI, TS, and Hb, and higher levels of sTfR and TIBC.
• High SII was associated with increased odds of ID and iron deficiency anemia (IDA).
• SII demonstrated significant correlations with sTfR, TIBC, SF, TBI, TS, Hb, ID, and IDA, and a stronger association with ID than CRP.

Conclusions:

• The systemic immune-inflammation index (SII) is independently associated with iron deficiency (ID) and iron deficiency anemia (IDA).
• SII serves as a potential indicator for systemic inflammation's impact on iron metabolism.
• The findings suggest SII may be a more comprehensive marker for ID than CRP.