Association between Leukocyte Count and Age, Body Mass Index, and Lifestyle-related Factors: a Cross-sectional Study in Ningen Dock Examinees

Abstract

Background: The reference range for leukocyte count is wide, and examination of factors affecting leukocyte count is important.

Methods: We conducted a cross-sectional study of apparently healthy Ningen Dock examinees who underwent a health check-up in 2012. Information regarding current medication and lifestyle habits was obtained via a self-reported questionnaire.

Results: Overall, 5,853 men and 4,447 women were included in the study. Multiple regression analyses revealed that leukocyte count in men was most strongly associated with the level of smoking, followed by body mass index (BMI), level of alcohol consumption, and frequency of exercise. Leukocyte count in women was most strongly associated with BMI, followed by level of smoking, age and level of alcohol consumption. When comparing groups stratified by age after adjusting for confounding factors, the mean leukocyte count in women was highest in the youngest group (age < 40 years; 5,295/μL) , gradually decreased as age advanced, and was lowest in those aged 50–59 years (4,638/μL). In contrast, the mean leukocyte count of men was constant (5,448–5,565/μL) across age groups. When comparing men and women in each age group, leukocyte count in women was lower in those aged =/> 50 years.

Conclusions: Leukocyte count was strongly associated with level of smoking and BMI in both men and women, but an association with age was observed only in women. We believe it is important to interpret leukocyte counts in Ningen Dock examinees, taking factors associated with leukocyte count into consideration.