Anabolic and Metabolic Effects of Testosterone and Other Androgens: Direct Effects and Role of Testosterone Metabolic Products

Abstract

Sex hormones play a major role throughout the body starting from gender differentiation in utero to senescence. While they are undoubtedly important for development and conservation of reproductive function, their importance has been shown in most systems by experimental and clinical models. While testosterone (T) is considered to be the most important androgen in circulation, it may either directly exert effects on target tissues or be metabolized by 5α-reductase into dihydrotestosterone (DHT) or aromatized to estradiol (E2). Differential effects of T and its metabolites are not well known and are a topic of scientific debate. These pleiotropic effects lead to variable phenotypes, clinical manifestations, and significance throughout life and may be more pronounced in some systems (such as bone and reproductive organs) or stages (such as puberty) than in others. This chapter focuses on the available clinical evidence of the androgen effects on several important systems.