Androstenedione is a prohormone from which steroids such as estrone or testosterone are formed in the organism. “Andros” in Greek means “the man,” and the chemical structure is derived from the word suffix “dion.” Both word syllables refer to the fact that it is a sex hormone that has a masculinizing (i.e. androgenic) effect and that it belongs to the ketones, which in turn are substances that combine an oxygen atom with a carbon atom through a double bond. Androstenedione is the precursor of various hormone syntheses. In the morning, the concentration of the pro-hormone in the blood shows the highest value and is subject to greater fluctuations in the course of the day. The hormone release varies and depends, for example, in women on their menstrual cycle.
What is androstenedione?
Most hormones affect a person’s sex life, emotions and behavior, but they are also important messengers that keep the organism in balance. They are released directly into the blood and influence biological processes, including growth and stress responses. With the help of cholesterol, hormones are formed that have a steroid skeleton and a side chain. These are called steroid hormones and form the sex hormones of the gonads and the corticosteroids of the adrenal cortex. They occupy receptors inside the cell and bind to estrogens and androgens, among others. The latter are both natural and synthetic hormones that condition the growth of male sexual characteristics and also generally have an androgenic effect. An important male sex hormone, for example, is testosterone, which is produced as a target cell from other hormones and is responsible for male appearance and behavior. Androstenedione also belongs to the group of these androgens. It is a steroid chemically and structurally similar to testosterone and is an intermediate in estradiobiosynthesis and testosterone formation. It is formed in the adrenal cortex and gonads, in the testes in males, and in the theca cell layer in females first, then in the ovaries and adrenal glands. Approximately ten percent of androstenedione is also formed peripherally by conversion from dehydroepiandrosterone, a steroid hormone most abundant in the human organism.
Function, effects, and tasks
The androgenic effect determines, for example, male attributes such as a strong body hair or an increase in total muscle mass, but also causes other side effects in women. A large amount of testosterone in the female body is produced from androstenedione and, when released in increased amounts, can lead to baldness, decreased breast development, infertility, increased production in the sebaceous glands, a deeper voice, acne or enlargement of the clitoris, or even the formation of pseudopenis while the internal genitalia are female. Other effects may include cavity formation in the ovaries or general cycle disturbances. The causes vary. Elevated levels may arise, for example, due to obesity, expressing themselves in particular as fat deposits in the abdominal and lumbar regions. This results in an increased output of insulin and thus an increase in androgens and also in androstenedione, since these hormones are stimulated by insulin. Under these circumstances, the tissue no longer responds to insulin, so all the more insulin is secreted by the pancreas as a countermeasure. This mechanism is called hyperinsulinism.
Formation, occurrence, properties, and optimal levels
Androstenedione is a lipophilic steroid hormone. It has a carbon chain of nineteen carbon atoms. In young women and men, androstenedione concentrations are similar. In women who are premenopausal, the concentration drops by fifty percent after ovariectomy, and in women who are postmenopausal, the concentration drops by twenty percent. As a biosynthetic precursor to estrone, androstenedione is converted to estrone in adipose tissue and in the granulosa cell layer of the follicle by the enzyme aromatase. It can be used together with testosterone as part of a primary diagnosis of disturbed androgen balance. The androstenedione level can also be increased by drugs that have a stimulating effect on synthesis with androgens or adrenocortical androgens. Such drugs can also lower the androstenedione level, e.g.B. by a serum such as glucocorticoids or by various ovulation inhibitors. Since the measured values vary greatly throughout the day, with the highest value in the morning but fluctuating greatly throughout the day, the blood sample is taken in the early follicle maturation phase. The androstenedione level may also change due to other causes, becoming higher, for example, in ovarian stromal hyperthecosis, obesity, tumors that produce androgens, hirsutism, or Cushing’s syndrome. It decreases in adrenocortical or ovarian insufficiency and in sickle cell anemia.
Diseases and disorders
The exact function of androstenedione has not been adequately studied, yet the pro-hormone finds use in synthetic production. For example, it is said to be an effective anti-aging product and allegedly counteracts aging of the skin. Androstenedione is also sold as a dietary supplement in some countries and has some supporters especially in the field of competitive sports, as it is said to stimulate increased testosterone formation and thus lead to an increase in athletic performance and muscle mass, although this has not been proven. On the contrary, androstenedione was put on the doping list by the Olympic Committee due to its multiple side effects and has been banned by many sports organizations. Such risks include hypertension, arteriosclerosis, impotence, prostate cancer, and the development of hormone-dependent tumors.
