The leucocyte count: correlates and relationship to coronary risk factors: the CARDIA study.

Correlates of the leucocyte count (WBC) and its relationships to other coronary heart disease (CHD) risk factors were assessed in 4981 black and white young adults. Mean WBC was higher in women than men, higher in whites than blacks, and higher in those aged 18-24 than aged 25-30 years. It also varied by season with the highest levels in the autumn. Other characteristics with persistent statistically significant direct associations with the WBC after multivariate adjustments were cigarette smoking, marijuana use, geographical location (possibly an inter-laboratory artifact), use of birth control pills, body mass index, pulse rate, and systolic blood pressure; height, physical fitness and high density lipoprotein cholesterol (HDL-C) level were inversely associated with the WBC. The negative association of WBC with HDL-C was too small to explain the association of WBC with CHD found elsewhere. The WBC is a commonly performed clinical test; yet much remains to be learned about its variation in the general population and its value as a predictor rather than merely an indicator of disease.