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The emergence of men’s health as a distinct discipline within internal medicine is founded on the wide consensus that men and women differ across their lifespan in their susceptibility to disease, in the clinical manifestations of the disease, and in their response to treatment. Furthermore, men and women weigh the health consequences of illness differently and have different motivation for seeking care. Men and women experience different types of disparities in access to healthcare services, and in the manner in which health care is delivered to them because of a complex array of socioeconomic and cultural factors. Attitudinal and institutional barriers to accessing care, fear, and embarrassment due to the perception that it is not manly to seek medical help, and reticence on the part of patients and physicians in discussing issues related to sexuality, drug use, and aging have heightened the need for programs tailored to address the specific health needs of men.
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The sex differences in disease prevalence, susceptibility, and clinical manifestations of the disease were discussed in Chap. 391 (Women’s Health) and will not be discussed here. It is notable that the two leading causes of death in both men and women—heart disease and cancer—are the same. However, men have higher prevalence of neurodevelopmental and degenerative disorders, substance abuse disorders, including the use of performance enhancing drugs and alcohol dependence, diabetes, and cardiovascular disease, and women have higher prevalence of autoimmune disorders, depression, rheumatologic disorders, and osteoporosis, The men are substantially more likely to die from accidents, suicides, and homicides than women. Among men, 15–34 years of age, unintentional injuries, homicides, and suicides account for over three-fourths of all deaths. Among men, 35–64 years of age, heart disease, cancer, and unintentional injuries are the leading causes of death. Among men ≥65 years of age, heart disease, cancer, lower respiratory tract infections, and stroke are the major causes of death.
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The biologic bases of sex differences in disease susceptibility, progression, and manifestation remain incompletely understood, and are likely multifactorial. Undoubtedly, sex-specific differences in the genetic architecture and circulating sex hormones influence disease phenotype; additionally, epigenetic effects of sex hormones during fetal life, early childhood, and during pubertal development may epigenetically imprint sexual and nonsexual behaviors, body composition, and disease susceptibility. The circulating and tissue concentrations of sex hormones differ substantially in men and women, and these hormonal differences may affect gene expression in cells of males and females in all parts of the body. The presence of only one X chromosome in men renders them more susceptible to X-linked disorders than women. Due to the X inactivation of one randomly chosen X chromosome, women’s bodies contain two epigenetically different cell populations. The genes that do not undergo X inactivation exhibit dosage differences between male and female cells. Expression of the Y chromosome genes in men may affect the function of somatic cells containing the Y chromosome. The differences in the imprinting of maternally ...