Serum androgen levels measure a class of steroid hormones called androgens that circulate in the bloodstream. These chemical messengers regulate various physiological processes throughout the body. The term “serum” indicates the measurement is taken from the liquid component of the blood after clotting, providing a snapshot of the body’s current hormonal status.
Androgen Types and Production Sites
Androgens are a group of C19 steroids, primarily including testosterone and dihydrotestosterone (DHT), which are the most potent forms. Other androgens include dehydroepiandrosterone (DHEA), its sulfated form (DHEA-S), and androstenedione. DHEA and androstenedione often function as precursor hormones, converting into more potent forms in peripheral tissues.
The primary sites of androgen production are the gonads and the adrenal glands. In males, the testes are the main source of testosterone, produced by the interstitial Leydig cells. The adrenal glands, located atop the kidneys, contribute precursor hormones, such as DHEA and DHEA-S, in both sexes.
In females, the ovaries produce a smaller, necessary amount of androgens, primarily testosterone and androstenedione, dependent on Luteinizing Hormone (LH). These ovarian and adrenal androgens are often converted into estrogens through a process called aromatization. Peripheral tissues like fat, skin, and muscle also convert weaker androgens into their more active forms, contributing to the body’s overall androgen level.
Physiological Roles in Males and Females
Androgens play a widespread role, affecting development, metabolism, and mood in both males and females. In males, androgens are responsible for the development of primary sex organs during embryonic development and drive pubertal changes. These changes include voice deepening, the growth of facial and body hair, and the maturation of sperm-producing tissues.
Throughout adulthood, androgens maintain the male reproductive system and preserve muscle mass and strength (anabolism). They also support bone density and contribute to red blood cell production (erythropoiesis). Furthermore, androgens act on the central nervous system, influencing sexual desire, mood, and cognitive functions.
In females, androgens are present at much lower concentrations but remain functionally important for several physiological processes. They serve as necessary precursors in the ovaries for the synthesis of estradiol and the creation of estrogen. Androgens also maintain female bone strength, muscle development, and sexual function, particularly libido. This hormonal balance is essential for ovarian function, including follicle development.
Measuring Serum Androgen Levels
Measuring serum androgen levels provides clinicians with diagnostic information for various hormonal symptoms. Testing is often used to diagnose conditions like infertility, irregular menstruation, or deficiency symptoms such as fatigue or loss of muscle mass. The procedure involves a simple blood draw, usually timed in the morning due to the natural daily fluctuation of androgen levels.
Two main measurements assess the body’s androgen status: Total Androgen and Free Androgen. Total androgen represents the entire amount of the hormone circulating in the blood, including both bound and unbound portions. The majority of androgens are bound to plasma proteins, primarily Sex Hormone-Binding Globulin (SHBG) and albumin.
Free androgen, making up only 1% to 3% of the total, is the biologically active portion not bound to proteins. This free hormone easily enters cells and binds to receptors to exert effects on the body’s tissues. Since conditions affecting protein binding (e.g., obesity or thyroid disorders) can skew the total measurement, testing both total and free levels provides a more accurate picture of hormonal activity. The Free Androgen Index (FAI), calculated from the ratio of total testosterone to SHBG, is also used, especially in women, to gauge available hormone.
Clinical Conditions Caused by Imbalance
Abnormal serum androgen levels can lead to specific clinical conditions, depending on whether levels are too high (hyperandrogenism) or too low (hypogonadism). Hyperandrogenism is most commonly observed in women, manifesting as various symptoms due to excessive hormonal action on tissues. Polycystic Ovary Syndrome (PCOS) is the most frequent cause of elevated androgens in reproductive-age women.
Symptoms of hyperandrogenism in women include hirsutism (excess hair growth in a male-like pattern), acne, and irregular or absent menstrual periods. Less commonly, very high androgen levels may be caused by rare conditions such as tumors in the adrenal glands or ovaries. Sustained high levels are also associated with metabolic issues, including insulin resistance.
Conversely, low androgen levels (hypogonadism) are a common concern in males, often leading to symptoms like low libido, erectile dysfunction, and fatigue. This deficiency can result in decreased muscle mass and reduced bone mineral density, increasing the risk of osteoporosis. In both males and females, androgen deficiency can cause a decline in well-being and is associated with chronic illness or stress.