Sex and gender differences in endocrinology

Abstract

Endocrinology deals with the physiology and pathophysiology of the endocrine system, the secretion and effects of the hormones, as well as the function of their receptors. The science of endocrinology studies the regulation of energy metabolism, body weight maintenance, and reproduction throughout the life cycle of men and women. Endocrine diseases go along with either overproduction or deficiency of hormones with far-reaching consequences on health and well-being of the patients. Endocrinology is important for studies with focus on sex and gender differences because hormones are the basis of many biological differences between both sexes. Sexual hormones are fundamental for sex differences, physiological sex development, puberty, menstrual function and fertility, and reproduction. Important sex differences also exist in regard to other endocrine systems such as thyroid hormones, insulin metabolism, the hypothalamic-pituitary-adrenal axis, bone metabolism, as well as adipocytokines. The endocrine functions interact with each other in a complex relationship including feedback mechanisms (Fig. 9.1). Two major endocrine/metabolic diseases, obesity and type 2 diabetes, represent chronic lifestyle-induced diseases with important sex- and gender-based differences. Both are dramatically increasing in prevalence causing high costs to the health care systems and are therefore of utmost importance for public health. Endocrinology also includes research on bone and its mineralization, in -particular osteoporosis. Osteoporosis and related complications are a major burden of postmenopausal females but also an increasing and often undetected health problem of males. Thyroid disorders, in particular immune-mediated thyroid diseases, are more frequently seen in women than men. On the other hand, type 1 diabetes, another immune-mediated and common endocrine disease which can lead to severe complications and increased mortality, shows similar prevalence in men and women. However, both types of diabetes, though with completely different underlying mechanisms and pathophysiology, increase the cardiovascular risk of women two- to threefold more than in diabetic males in comparison to nondiabetic subjects of the same sex. As a consequence diabetes-related mortality is even higher in women than men.