Men produce a wide range of hormones, not just testosterone. While testosterone is the dominant sex hormone in the male body, men also rely on estrogen, progesterone, growth hormone, cortisol, insulin, and several signaling hormones that keep the entire system running. Each plays a distinct role, and they constantly interact with one another.
Testosterone: The Primary Male Hormone
Testosterone is the hormone most people associate with men, and for good reason. It drives the development of masculine physical traits during puberty and maintains them throughout life. Testosterone supports muscle strength and mass, bone density, fat distribution, facial and body hair growth, red blood cell production, sex drive, and sperm production. It’s produced primarily in the testes, in specialized cells called Leydig cells, which convert cholesterol into testosterone.
Normal testosterone levels for adult men (ages 18 and older) range from 193 to 824 ng/dL, according to Cleveland Clinic reference ranges. During puberty, levels can spike as high as 1,010 ng/dL. After about age 30, testosterone declines at roughly 1% per year. This gradual drop becomes more noticeable over decades and is sometimes called late-onset hypogonadism or, informally, “andropause.” When testosterone falls below about 300 ng/dL, men are more likely to experience symptoms like low libido, erectile dysfunction, reduced muscle mass, increased body fat, lower bone density, and depressed mood.
Not all testosterone in your blood is equally active. A protein made in the liver called sex hormone-binding globulin (SHBG) binds to testosterone and prevents it from interacting with tissues. Only the unbound, or “free,” portion of testosterone actually works in your body, supporting functions like bone and muscle growth. This is why doctors sometimes test both total and free testosterone. If SHBG is high, your total testosterone might look normal while too little is actually available to your cells.
DHT: Testosterone’s More Potent Form
Dihydrotestosterone, or DHT, is made when an enzyme converts testosterone into a more powerful form. It’s the most potent androgen in the body. During fetal development, DHT is essential for forming male external genitalia. In adults, it’s the primary driver behind skin and prostate changes.
DHT stimulates prostate cell growth, which is harmless in younger men but becomes a problem with age. It plays a central role in benign prostatic hyperplasia (BPH), the prostate enlargement that affects most men as they get older. DHT is also the hormone behind male-pattern hair loss. It miniaturizes hair follicles on the scalp while simultaneously promoting body and facial hair growth. This is why medications that block the conversion of testosterone to DHT are used to treat both prostate enlargement and hair loss.
LH and FSH: The Control Signals
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are produced in the pituitary gland, a small structure at the base of the brain. They don’t build muscle or grow hair. Instead, they act as messengers that tell the testes what to do.
LH travels through the bloodstream to the testes and triggers Leydig cells to produce testosterone. Without LH, testosterone production essentially stops. FSH targets a different set of cells in the testes called Sertoli cells, which support sperm development. While FSH isn’t strictly required to maintain sperm production once it’s already established, it is critical for achieving normal sperm counts. Men who lack both LH and FSH, a condition called hypogonadotropic hypogonadism, have extremely low testosterone and are typically infertile. This illustrates how dependent the entire system is on these two signaling hormones.
Estrogen in the Male Body
Men produce estrogen, and it’s not just a leftover from female biology. Estradiol, the main form of estrogen in men, is made when an enzyme called aromatase converts testosterone into estrogen. This happens in fat tissue, the brain, bone, and the testes themselves.
Estradiol is essential for male bone health. Without adequate estrogen, men lose bone density just as postmenopausal women do. It also plays a direct role in sexual function. In the brain, estradiol synthesis increases in areas related to sexual arousal, and it modulates libido and erectile function. In the testes, estrogen influences every stage of sperm development, from the signaling hormones down to the maturation of sperm cells themselves. Men don’t need much estrogen compared to women, but they absolutely need some.
Progesterone’s Role in Men
Progesterone is typically thought of as a female hormone, but men produce small amounts of it in the adrenal glands and testes. It serves as a chemical building block in the pathway that produces testosterone. Beyond that precursor role, progesterone influences sperm development and helps sperm undergo the final activation steps needed to fertilize an egg. It’s a minor player in terms of volume, but it contributes to both fertility and hormone production.
DHEA: The Precursor Hormone
Dehydroepiandrosterone, or DHEA, is produced mainly by the adrenal glands that sit on top of the kidneys. It functions as a raw material that the body converts into both testosterone and estrogen through a series of chemical steps. DHEA first becomes androstenedione, which then converts to testosterone, which can further convert to either DHT or estradiol.
DHEA also circulates freely in the blood (unlike testosterone, which partially binds to SHBG) and acts on the brain as a neurosteroid. DHEA levels peak in a man’s 20s and decline steadily with age, which is one reason it has drawn attention as a supplement. However, because it feeds into multiple hormonal pathways, supplementing with it has unpredictable effects on the balance between androgens and estrogens.
Growth Hormone
Growth hormone is released by the pituitary gland and affects nearly every tissue in the body. In children and adolescents, it drives height and skeletal growth. In adult men, it continues to regulate body composition by increasing protein synthesis, stimulating fat breakdown, and supporting lean body mass. It also contributes to bone metabolism, fluid balance, glucose and fat metabolism, exercise performance, and heart function.
Growth hormone secretion is highest during deep sleep and declines with age. When levels drop significantly, men tend to gain body fat (particularly around the midsection), lose muscle mass, and recover more slowly from physical exertion.
Cortisol and Its Effect on Testosterone
Cortisol is the body’s primary stress hormone, released by the adrenal glands in response to physical or psychological stress. In short bursts, it’s useful: it raises blood sugar for quick energy, reduces inflammation, and sharpens alertness. But chronically elevated cortisol directly suppresses testosterone production.
The mechanism appears to work at the level of the testes. Research shows that high cortisol disrupts the ability of Leydig cells to produce testosterone, likely by interfering with the enzymes needed for testosterone synthesis and reducing the effectiveness of LH signaling. This means prolonged stress, poor sleep, or overtraining can lower testosterone not through some vague “stress effect” but through a specific biochemical disruption in the testes themselves.
Insulin’s Connection to Testosterone
Insulin, the hormone that regulates blood sugar, has a direct relationship with testosterone. In healthy men, the two systems work in balance. But in insulin-resistant states like type 2 diabetes or obesity, chronically high insulin levels suppress testosterone production in the Leydig cells of the testes. This happens even when LH and FSH levels remain normal, meaning the brain is still sending the right signals but the testes can’t respond properly.
The relationship runs both directions. Low testosterone itself worsens insulin sensitivity, creating a cycle where excess weight drives down testosterone, which makes it harder to lose weight, which keeps insulin high. Restoring testosterone in men with low levels due to type 2 diabetes has been shown to improve insulin sensitivity by shifting body composition toward more lean mass and less fat.
Prolactin
Prolactin is best known for its role in breastfeeding, but men produce it too, in small amounts. Normal levels for men are below 20 ng/mL. At normal levels, prolactin’s role in men isn’t fully understood, but it may contribute to immune regulation and reproductive function.
What matters more practically is when prolactin goes too high, a condition called hyperprolactinemia. In men, elevated prolactin causes loss of sex drive, erectile dysfunction, and infertility. It can be caused by pituitary tumors (usually benign), certain medications, or other hormonal imbalances. Because its symptoms overlap heavily with low testosterone, high prolactin is sometimes the hidden cause when testosterone replacement alone doesn’t resolve a man’s symptoms.