Normal androgen levels in a human being vary according to sex, age, and other factors. Androgens, a category that includes chemicals such as testosterone, dihydrotestosterone, and dehydroepiandrosterone, are hormones responsible for producing male sexual characteristics, a process called virilization. They are also present in lower quantities in females as well. Normal levels of the primary androgen, testosterone, in adult males can be as low as 270 nanograms per deciliter (ng/dL) and as high as 1,080 ng/dL, depending on age, while women normally have 70 ng/dL or less. Abnormal androgen levels can cause health problems and other abnormalities in both men and women, and excessive or insufficient amounts of androgens during childhood or in utero can affect development.
Androgen levels in males peak between the ages of 20 and 40, when testosterone levels can rise to as much as 1,080 ng/dL. It declines to between 350 and 890 ng/dL in the next two decades of life, and to between 350 and 720 ng/dL after the age of 60. Prepubescent boys usually have less than 30 ng/dL, but rise to between 100 and 540 ng/dL by their mid-teens and as high as 970 ng/dL by their late teens. This change brings about the maturation of the reproductive organs, along with other physical changes such as increased muscle mass, increased facial and body hair, and a deeper voice.
Women normally have much lower amounts of androgens in their bodies, but are physiologically more sensitive to them. Premenopausal adult women have normal have testosterone levels between 10 and 70 ng/d. This amount usually triples or quadruples during pregnancy and drops to less than 40 ng/dL after menopause. Prepubescent girls normally have less than 10 ng/dL, rising to 8–53 ng/dL during adolescence. Abnormally high amounts of androgens in a woman's body can cause the development of masculine secondary sexual traits such as a deeper voice, increased muscle mass, and increased facial and body hair growth, as well as symptoms such as acne and menstrual abnormalities.
Androgens in the womb, and especially dihydrotestosterone, are an important influence on fetal development, causing development of the penis, scrotum, and other components of the male reproductive system. Abnormal androgen levels can cause abnormalities of sexual development such as congenital adrenal hyperplasia, in which a child who is genetically female develops partially male characteristics or ambiguous genitalia. In childhood, abnormal androgen levels can cause delayed or precocious puberty.
Some men's bodies produce abnormally low levels of testosterone or other androgens, a condition called hypogonadism. Common symptoms include reduced muscle mass, reduced beard and body hair growth, and sexual dysfunctions such as impotence or infertility. Hypogonadism has a variety of potential causes including genetics, infection, and malnutrition. The most common congenital cause of hypogonadism in males is Klinefelter syndrome, a genetic disorder caused by the presence of an extra X chromosome.
The effects of low androgen levels in women are less dramatic, but can include loss of sex drive. In both sexes, decreased androgen production and especially decreased testosterone production can cause depression, anxiety, or obesity. It also increases the risk of developing conditions such as heart disease and osteoporosis.