Cigarette smoking and male reproduction

The effects of cigarette smoking on male reproduction were studied through measuring the serum estradiol (E2), prolactin (PRL), and total testosterone (T). Smoking men had higher levels of E2 and PRL but normal T compared to nonsmokers. Raised E2 and PRL may be among the mechanisms through which cigarette smoking impairs male reproduction.Male cigarette smokers have been found to have a lower proportion of motile sperm than nonsmokers, and some studies have reported an increased proportion of abnormal sperm in smokers. To further assess the effects of cigarette smoking on male reproduction, serum levels of estradiol (E2), prolactin (PRL), and total testosterone (T) were compared in 50 heavy smokers (median 23.5 cigarettes/day) and 35 men who never smoked. The median age was 25.4 years among smokers and 27.4 years among nonsmokers. The differences between these 2 groups of men in terms of E2 and PRL levels were significant. Smokers showed elevated E2 levels (median, 59.8 pcg/ml + or - 1.83) compared with nonsmokers (median, 48.6 pcg/ml + or - 0.9) (p 0.001). The median serum PRL level was 10.11 ng/ml + or - 0.55 in smokers compared with 7.88 ng/ml = or - 0.54 in nonsmokers (p 0.001). The median level of serum T did not differ significantly between smokers (4.53 ng/ml + or - 0.17) and nonsmokers (4.55 ng/ml + or - 0.24). Of interest is the finding that smoking appears to elevate E2 in men, while it lowers E2 in women. Since estrogen is a strong stimulus for PRL secretion, the elevated E2 level in smokers may be the mechanism that produces raised serum PRL as well. The finding of a lack of difference between smokers and nonsmokers in T levels suggests that the steroidogenic function of the testis is not affected by smoking; on the other hand, smoking may affect the free fraction of T.