Men make about 20 times more testosterone daily, yet women are more sensitive
Testosterone is often cast as the male hormone, and adult men do carry seven to eight times the levels found in women, producing about 20 times as much each day. But women's bodies respond more sensitively to it, and in both sexes it shapes mood, thinking, metabolism, heart health and bone strength.
Chemically, testosterone is a steroid built in several steps from cholesterol and broken down in the liver. It works by binding the androgen receptor. It is made mainly in the testicles and, in smaller amounts, the ovaries. Some of it is converted into dihydrotestosterone, which grips the same receptor more tightly, and some into the oestrogen estradiol, so its effects are partly delivered by other hormones.
Its influence starts before birth. Between four and six weeks of gestation, androgens begin shaping the genitals, though dihydrotestosterone plays the larger part there. In the second trimester, testosterone and anti-Müllerian hormone steer the development of internal reproductive ducts, and prenatal androgen levels may predict gender-typed behaviour better than adult levels do, with moderate effects on spatial skills. Oddly, male infants experience a surge to pubertal levels in their first weeks, fading by four to seven months; its purpose in humans remains unknown, though one theory links it to brain masculinisation, which happens when testosterone is converted to estradiol inside the brain.
At puberty, sustained higher levels bring the familiar changes: stronger muscles, broader shoulders, a deeper voice and Adam's apple, facial and body hair, reshaped jaw and brow bones, oilier skin and sometimes acne. Its effects are often sorted into anabolic ones, building muscle and bone, and androgenic ones, driving male characteristics, though the categories overlap a great deal. Growth eventually stops as bones mature, a step that happens indirectly through estradiol and more gradually in men than in women.
Balance matters. Low levels in men are associated with frailty, fat accumulation, anxiety, depression and bone loss; high levels with male-pattern baldness and a greater risk of heart failure. Doctors prescribe testosterone for hypogonadism and breast cancer, and sometimes for age-related decline. The World Anti-Doping Agency bans it at all times as an anabolic agent.
Source: Testosterone
