Abstract

NICOTINE AND HORMONES: A SCIENTIFIC EXPLORATION OF SMOKING’S EFFECT ON THE HYPOTHALAMIC-PITUITARY-GONADAL AXIS IN MALES

Ali Nahedh Abdulameer*, Mohammed. K. S. Alquraishi, Samah Amer Hammood, Jenan Mahdi Ghani, Mustafa H. AlFatlawi

ABSTRACT

Cigarette smoking is a well-established disruptor of endocrine and reproductive function in males. This review synthesizes evidence from over 1,000 peer-reviewed studies, focusing on the impact of tobacco exposure on sex hormone profiles, sperm quality, and hypothalamic-pituitary-gonadal (HPG) axis regulation. Despite paradoxically elevated levels of total testosterone observed in moderate and heavy smokers, increased sex hormone-binding globulin (SHBG) concentrations lead to reduced bioavailable testosterone, impairing androgen-dependent functions. Age-stratified analyses reveal transient elevations in young males and marked hormonal decline among older individuals due to oxidative damage and diminished Leydig cell reserve. Moreover, smokers exhibit significant declines in sperm count, motility, and DNA integrity, despite serum testosterone levels. Elevated SHBG and disrupted gonadotropin secretion furthercontribute to subfertility and endocrine dysfunction. Importantly, clinical trials confirm that smoking cessation can restore hormonal balance and improve reproductive outcomes within six months. These findings highlight the need for routine endocrine evaluation in male smokers and reinforce cessation efforts in the management of reproductive and metabolic health.

Keywords: Cigarette smoking, Male endocrine function, Sex hormones, Testosterone, SHBG (Sex Hormone-Binding Globulin), Fertility, Hypothalamic-pituitary-gonadal axis, Nicotine.