Testosterone and Estrogen are the primary sex hormones produced in the body. These hormones are responsible for the primary sex characteristics of males and females, with testosterone giving male sex characteristics and estrogen giving female. However, both males and females produce both hormones, one just to a lesser extent than the other in respective sexes.
Testosterone is produced from its cholesterol substrate and almost exclusively binds to the blood proteins albumin (37-38%) and sex hormone binding globulin (SHBG) (60%). The remaining portion of testosterone that is not bound to blood proteins is the active constituent and labelled as “free testosterone”. Exogenous testosterone administration can bind to an androgen receptor and promote intracellular transcriptional and translational events that ultimately increase fat-free mass (muscle hypertrophy).
Testosterone’s functions can be classified into two categories – anabolic and androgenic. Androgenic means it provides the secondary sex characteristics that differentiate the men from women. Higher testosterone causes secondary male characteristics like facial hair, oily skin, maturation of genitalia, and a deep voice. Even our psychological traits are dependent on testosterone. For example, women are perceived to be less aggressive than men. This can be attributed to lower levels of testosterone in females.
Increase in endogenous testosterone leads to the conversion of testosterone to either DHT or estrogen. Increase in DHT leads to male pattern baldness and increased oil production that often leads to adult acne. Conversion of exogenous testosterone to estrogen may lead to the growth of breast tissue in men known as gynecomastia. In addition, the use of exogenous testosterone may lead to increased blood pressure, testicular atrophy, decreased sperm count, and impotence. In females, it may lead to menstrual irregularities, masculinization, and clitoromegaly (abnormal enlargement of the clitoris).
As an anabolic hormone, testosterone promotes functions such as regulating protein synthesis, fat metabolism, bone formation, strength and muscle mass. These anabolic effects are highly sought after from young to old men seeking to enhance their muscle mass and strength. However, the level of testosterone can fluctuate with age, training, and other internal and external variables that may decrease levels. Most changes that occur in testosterone level have no related cause. Thus, there is no way to prevent it.