*2.2.3 The role of testosterone*

In males, testosterone is the predominant sex hormone [6, 9]. It plays a number of important roles. These roles include;


Therefore, males in adolescent stages of life, who have too little testosterone may not experience normal masculinization. The genitals of such males may not enlarge, as well as their facial and body hair may be scanty. The voice may also not deepen as normally expected [5].

Notably, testosterone also helps in the maintenance of normal mood [7]. Scholars have argued that there may be other important functions of this hormone, testosterone, that have not yet been discovered [5].

To control the production of testosterone in men, signals have to be sent from the hypothalamus in the brain to the pituitary gland at the base of the brain. In turn, the pituitary gland then relays signals to the testes to produce testosterone [4]. Thus, a "feedback loop" closely regulates the amount of this hormone in the blood. Notably, when the level of testosterone rise too high, the brain (hypothalamus) then sends signals to the pituitary to reduce the production [5]. See **Figure 1** about the 'Hypothalamo-pituitary-testicular Axis'.

For normal working of the ovaries in females, there must be proper balance between testosterone and estrogen. It is a known fact that androgens also play an important role in normal brain functions, including mood, sex drive and cognitive functions, although these areas may still require more studies [1–5].

#### *2.2.4 Too little testosterone*

A range of symptoms can occur if testosterone production drastically drops below normal [7]. In past few years, scholars have focused on the effects of testosterone deficiency among men. As already known, that as men grow older, their levels of testosterone drop gradually, about 1–2% each year. The rate of this drop is slower compared to the relatively rapid drop in estrogen in females that culminates in menopause [5]. Majority of men, more than a third, who are above 45 years of age, have reduced levels of testosterone [5].

The following symptoms of deficiency of testosterone in adult males occur: they are but not limited to;


Indeed some men who have testosterone deficiency have related symptoms or conditions. These symptoms or conditions appear to improve when testosterone replacement is done [4, 5, 9].

Therefore, in a nutshell, men with low levels of testosterone might notice a reduction in body hair, muscle mass and strength, while women with too much testosterone might notice an increase in these traits [8].

#### *2.2.5 Too much testosterone*

Having too much naturally-occurring testosterone is not a common problem among men [5]. Too much testosterone is common only in male athletes who inject themselves with the hormone in order to make use of its anabolic effects. This is because anabolic steroids, testosterone or related hormones, increase muscle mass and athletic performance [5].

Thus, problems associated with abnormally high testosterone levels in men include but not limited to;

a.Low sperm counts, shrinking of the testicles and impotence

b.Heart muscle damage and increased risk of heart attack


k.Increased muscle mass

l.Increased risk of blood clots

m.Stunted growth in adolescents

n.Uncharacteristically aggressive behavior

o.Mood swings, euphoria, irritability, impaired judgment and delusions

On another hand, women with too much testosterone may grow facial hair, develop a deeper voice or experience decreased breast size. Too much testosterone in women can also cause acne [8].

Among women, perhaps the most common cause of a high testosterone level is polycystic ovary syndrome (PCOS). It affects 6–10% of premenopausal women [5, 7].

Therefore, women with too much testosterone might notice an increase in these traits; body hair, muscle mass and strength [8].
