Distribution of Blood Eosinophil Count in the Chinese General Population

Background Current clinical assessments of blood eosinophil (EOS) count often overlook demographic variability, particularly in Asian populations, where large-scale data remain scarce. We aimed to define demographic-specific distributions of EOS counts and identify factors associated with elevated levels in the general Chinese population. Methods Using the large-scale Chinese health-check population dataset comprising over 680 000 participants (2010–2023), we conducted a cross-sectional study to characterize overall and demographic-stratified distributions of blood eosinophil counts and construct age- and sex-specific percentile curves. We then applied multivariable regression to quantify associations between EOS counts and selected respiratory and systemic conditions, adjusting for key demographic and clinical covariates. Robustness was evaluated through sensitivity analyses. Results EOS counts showed a right-skewed distribution (median 100 cells·μL⁻ 1 , IQR 60–170) and were consistently higher in males than females (120 [80–200] versus 90 [50–140]). Age- and sex-specific centile curves defined population-based reference ranges and demonstrated a U-shaped trajectory across age. In multivariable analyses, higher EOS counts were associated with male sex, age <20 or ≥70, smoking, and higher BMI. EOS counts were positively associated with major respiratory conditions, including asthma and COPD, as well as selected systemic comorbidities (all P _Bonferroni <0.05). Findings were robust in sensitivity analyses. Conclusions In this large Chinese health-check population, blood eosinophil counts showed substantial demographic heterogeneity. These findings support age- and sex-stratified reference ranges and may inform more context-specific thresholds for eosinophilia in clinical practice.