Its primary action is nitrogen retention and stimulation and maintenance of the growth, development, and function of male secondary sexual characteristics. It is responsible, among other things, for the appearance of hair, the lowering of the tone of voice in puberty, the development of libido, the increase in muscle mass and sexual function (spermatogenesis or ovarian functioning).
Testosterone also performs other functions, for example, it also participates in the metabolism and appearance of skin pigmentation by solar radiation.
In humans, testosterone testabol enanthate 250 mg/ml (10 ml) is produced by Leydig cells in the testes and by the glands of the adrenal cortex; in women, however, this hormone is produced by the ovaries and adrenal glands, and its levels vary naturally due to the effect of age and pregnancy: during puberty and gestation testosterone peaks, while it decreases during menopause and in old age.
The level of testosterone in the plasma varies according to the circadian rhythms: in the morning its production is higher, while at night it touches the minimum level. There are no standard testosterone values, but conventionally it is defined as abundant when the total testosterone exceeds 12 nmol / l (nanomoles per liter) and deficient when it is below 8 nmol / l. Testosterone deficiency is known as hypogonadism.
Testosterone is distinguished in free, that is, circulating active in the blood, and bound or inactive: the latter is about 98% of the total testosterone in men and 99% in women. The adjective “bound” indicates that testosterone is bound to plasma protein molecules, usually sex hormone-binding globulin (SHBG) or albumin.
The balance between free and bound testosterone is maintained by the body, so if their relationship is altered, chemical and biological mechanisms intervene which restore the correct proportions. For example, if an excessive increase in free testosterone occurs, it is transformed into estradiol, a typically female hormone, and the synthesis of testosterone in the testes is reduced.
Its deficiency contributes to cause some serious pathologies, for example, obesity, osteoporosis, erectile dysfunction, impotence, reduction of breast size, infertility, depression, irritability, inability to concentrate and cardiovascular diseases.
Equally risky are the effects of an excess of testosterone, primarily low sperm count ( oligospermia ), reduced fertility, impotence, enlarged prostate and difficulty urinating, high blood pressure, elevated cholesterol, mood swings.
Scientific literature has tried to demonstrate the correlation between testosterone levels and the risk of prostate cancer, but at the moment there is no evidence yet.