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This article reports on the relationship between cigarette smoking, white blood cell count (WBC), platelet count (PC), and hematocrit in a Norwegian adolescent population. Data were obtained on 439 youths, 14 to 16 years old, as part of the Oslo Youth Study, an investigation of risk factors and behaviors for cardiovascular disease and cancer among adolescents. Analyses of covariance, controlling for height, weight, age, sexual maturation, high-density lipoprotein (HDL) cholesterol, and hematocrit revealed that both male and female regular smokers (those reporting smoking at least once a week) had significantly higher mean WBCs. Male regular smokers also had significantly higher PCs than nonsmokers, and female regular smokers had higher PCs than young women who smoked less often than once a month. Hematocrit, after adjustment for height, weight, age, sexual maturation, and HDL cholesterol, was significantly lower in male regular smokers, while female regular smokers had higher hematocrit values than nonsmokers or occasional smokers. Results of this study show that WBC and PC were increased in adolescents who started smoking relatively recently. This indicates that the increase in white cell count observed in smokers is unlikely to be due to a longstanding smoking-induced chronic disease condition.Circulation 72, No. 5, 971-974, 1985. STUDIES have shown that for adults, white blood cell count (WBC) is significantly higher in current cigarette smokers than in nonsmokers or former smokers. 13 Furthermore, WBC has been found to be a strong predictor of myocardial infarction4' 5 and to be independently related to cardiovascular disease (CVD) and cancer mortality.3 Although these associations do not necessarily indicate causality, one hypothesis that has been put forward is that increased WBC reflects cellular injury of importance in both CVD and cancer. While cardiovascular and cancer mortality end points obviously cannot readily be studied in preadult populations, the relationship between cigarette smoking, WBC, and other related variables can be studied in any age group in which cigarette smoking is prevalent. However, such studies have typically been conducted in adult populations.Most regular adult smokers have been smoking for a

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The relationships of serum total cholesterol, high density lipoprotein (HDL) cholesterol and fasting triglycerides (adjusted for body mass index, wt/ht2) with stages of pubertal development were examined in a Norwegian population of 920 adolescents, aged 10 to 16 years. For 13- and 14-year-olds, all five stages of Tanner's maturity index were represented. For the whole population, total serum cholesterol showed a larger decrease when related to sexual maturity stage than to chronologic age. For females, HDL cholesterol and triglycerides increased significantly when related to age in years; this was not found when related to the maturity index. Triglycerides showed a larger increase when related to chronologic age in males as compared with sexual maturity stage. Both among 13- and 14-year-old males, the most mature had significantly lower values for total cholesterol than the least mature. For 12-year-old males, HDL cholesterol decreased significantly with increasing sexual maturation. Among females, the more mature 12-year-olds had significantly lower values for total cholesterol compared with the less mature. Early maturing 13-, 14- and 15-16-year-olds had lower levels of HDL cholesterol compared with late maturers. These findings suggest that age in years may be a poor index of development in adolescents and that a measure of physiologic developmental age should be included in epidemiologic studies of serum lipids among adolescents.