Testosterone is the most important sex hormone in men. Low levels of testosterone production can cause decreased sexual function, loss of male characteristics, and mood changes.
Low Testosterone Overview
Testosterone is the most important sex hormone that men have. It is responsible for the typical male characteristics, such as facial, pubic, and body hair; muscle strength and mass; and a deep voice. Testosterone also helps maintain sex drive and sexual function, sperm production, red blood cell production, and bone health. The brain and pituitary gland (a small gland at the base of the brain) control the production of testosterone by the testes.
In adult men, low testosterone levels (also called hypogonadism) can cause a decrease in sex drive, poor erections, low sperm count, and enlarged breasts. Over time, low testosterone may cause a man to lose body hair, muscle mass, and strength and to gain body fat. Long-term low testosterone may also cause weak bones (osteoporosis), mood changes, decreased energy, and smaller testes.
A man's testosterone level normally decreases with age. Approximately 4 out of 10 men over the age of 45 have low testosterone levels.
Low testosterone can result from injuries, infections, medications, chronic diseases, or genetic conditions. Testosterone replacement therapy can improve symptoms of low testosterone.
Low Testosterone Symptoms
Hypogonadism can begin during fetal development, before puberty, or during adulthood. Signs and symptoms depend on when the condition develops.
If the body does not produce enough testosterone during fetal development, the result may be impaired growth of the external sex organs. Male hypogonadism may delay puberty or cause incomplete or lack of normal development.
In adult males, low levels of testosterone may alter certain masculine physical characteristics and impair normal reproductive function. Signs and symptoms may include:
- erectile dysfunction
- decrease in beard and body hair growth
- decrease in muscle mass
- development of breast tissue (gynecomastia)
- loss of bone mass (osteoporosis)
Low testosterone levels can also cause mental and emotional changes. As testosterone decreases, some men may experience symptoms similar to those of menopause in women, including:
- decreased sex drive
- difficulty concentrating or remembering things
- hot flashes
- insomnia or other sleep disturbances
- decreased motivation or self-confidence
Low Testosterone Causes
Male hypogonadism means the testicles do not produce enough of the male sex hormone testosterone. There are 2 basic types of hypogonadism:
Primary. This type of hypogonadism — also known as primary testicular failure — originates from a problem in the testicles.
Secondary. This type of hypogonadism indicates a problem in the hypothalamus or the pituitary gland — parts of the brain that signal the testicles to produce testosterone.
Possible secondary causes of low testosterone include:
- Testicular injury or infection. Trauma or castration can cause the testes to produce lower than normal levels of testosterone.
- Inflammatory disease. Certain inflammatory diseases, such as sarcoidosis, histiocytosis, and tuberculosis, involve the hypothalamus and pituitary gland and can affect testosterone production, causing hypogonadism.
- HIV/AIDS. HIV/AIDS can cause low levels of testosterone by affecting the hypothalamus, the pituitary gland, and the testes.
- Chronic diseases. Diseases such as liver and kidney disease and type 2 diabetes can contribute to low levels of testosterone.
- Medications. The use of certain drugs, such as opiate pain medications and some hormones, can affect testosterone production.
- Obesity. Being significantly overweight at any age may be linked to hypogonadism.
- Normal aging. Older men generally have lower testosterone levels than younger men do. As men age, there's a slow and continuous decrease in testosterone production.
- Concurrent illness. The reproductive system can temporarily shut down due to the physical stress of an illness or surgery, as well as during significant emotional stress. This is a result of diminished signals from the hypothalamus and usually resolves with successful treatment of the underlying condition.
Both primary and secondary hypogonadism may be caused by an inherited (congenital) trait or something that happens later in life (acquired), such as an injury or an infection. At times, primary and secondary hypogonadism can occur together.
Risk factors for hypogonadism include:
- Kallmann syndrome
- undescended testicles as an infant
- mumps infection affecting your testicles
- injury to your testicles
- testicular or pituitary tumors
- Klinefelter syndrome
- previous chemotherapy or radiation therapy
- untreated sleep apnea
Low Testosterone Diagnosis
Doctors base a diagnosis of hypogonadism on physical symptoms and results of blood tests that measure testosterone levels. During a physical exam, your doctor will examine your body hair, size of your breasts and penis, and the size and consistency of the testes and scrotum. Your doctor can also use blood tests to see if your total testosterone level is low. Because testosterone levels vary and are generally highest in the morning, blood testing is usually done early in the day, often between 7 and 10 a.m.
Further testing can determine if a testicular disorder or a pituitary abnormality is the cause. These studies may include:
- hormone testing
- semen analysis
- pituitary imaging
- genetic studies
- testicular biopsy
Early detection of low testosterone production in boys can help prevent problems from delayed puberty. Early diagnosis and treatment in men offer better protection against osteoporosis and other related conditions.
Living With Low Testosterone
Adult men can take several steps to maintain their overall health as they manage low testosterone levels.
Prevent osteoporosis. Lifestyle and dietary changes can help prevent osteoporosis. Regular exercise and adequate amounts of calcium and vitamin D maintain bone strength and are important for reducing the risk of osteoporosis.
Learn about erectile dysfunction or infertility. The conditions caused by low testosterone can cause psychological and relationship problems. Know what to expect from these conditions and what to do if new or uncomfortable feelings develop between you and your partner.
Reduce stress. Talk with your doctor about how you can reduce the anxiety and stress that often accompany these conditions. Many men benefit from psychological or family counseling.
Find support. Support groups can help people with hypogonadism and related conditions cope with similar situations and challenges. Helping your family understand the diagnosis of hypogonadism also is important.
Low Testosterone Treatments
Treatment for male hypogonadism depends on the cause and whether you are concerned about fertility. For adult men, testosterone replacement therapy can improve sexual interest, erections, mood and energy, body hair growth, bone density, and muscle mass.
Testosterone replacement has been shown to:
- improve energy
- improve sex drive
- increase muscle mass
- lower body fat
- help sleep
- improve erections
- raise energy level
- improve mood
Testosterone treatment may also increase bone mineral density and lower the risk for broken bones. Testosterone treatment is a life-long therapy, just like in other chronic conditions. Stopping treatment will result in low levels.
Testosterone replacement therapy can be given using:
Skin gel. Depending on the brand, you either rub testosterone gel into your skin on your upper arm or shoulder (AndroGel, Testim), apply with an applicator under each armpit (Axiron), or pump on your inner thigh (Fortesta). As the gel dries, your body absorbs testosterone through your skin.
Shots. Testosterone injections are given in a muscle. Injections are a safe and effective way to replace testosterone. You or a family member can learn to give testosterone injections at home. Testosterone undecanoate (Aveed), an injection recently approved by the Food and Drug Administration, is injected less frequently but must be administered by a health care provider and can have serious side effects.
Long-acting pellets. Testosterone-containing pellets (Testopel) are surgically implanted under the skin and slowly release testosterone. The pellets need to be placed every 3 to 6 months.
Patches. A testosterone-containing patch (Androderm) is applied each night to your back, abdomen, upper arm or thigh. The site of the application is rotated to maintain 7-day intervals between applications to the same site, to lessen skin reactions.
Tablets that stick to the gums or cheek. A small putty-like substance that contains testosterone (Striant) is placed in your gum or cheek area delivers testosterone through the natural depression above your top teeth where your gum meets your upper lip (buccal cavity). This product quickly sticks to your gumline and allows testosterone to be absorbed into your bloodstream.
Testosterone is also available in pill form, but taking testosterone orally is not recommended for long-term hormone replacement because it might cause liver problems.