Reference intervals of systemic immune-inflammation index, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio, mean platelet volume to platelet ratio, mean platelet volume and red blood cell distribution width-standard deviation in healthy Han adults in Wuhan region in central China.

Low-grade inflammatory indicators are widely used in the diagnosis and prognosis of different diseases, particularly, in cancers. The establishing of reference intervals (RIs) are necessary to provide baselines for the interpretation and application of the indicators in clinical. A retrospective review was organized to include ostensibly healthy subjects aged >18 years old to establish RIs based on gender and age for systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), mean platelet volume-to-platelet ratio (MPV/PLT), MPV and red blood cell distribution width - standard deviation (RDW-SD). Another 5012 healthy persons were included to validate the RIs. The differences among gender, age, and Body Mass Index (BMI) groups were compared to assess their influences on each indicator. A total of 26,242 males and 11,934 females were included. All indicators differed between males and females except NLR. Compared with males, the values of SII, PLR, MPV and RDW-SD were higher while MPV/PLT lower in females. The values of SII, NLR and PLR increased with age in females between 18 and 50 years old, declined in 51-60 years old group, then increased with age again. Values of MPV/PLT and RDW-SD increased with age. The values of SII increased with BMI while PLR, MPV, and MPV/PLT decreased. We effectively established RIs for the indicators. They will help with predicting disease progression in various clinical practices. Gender, age, and BMI were suggested to be taken into consideration when these parameters were applied in clinical.