Hypogonadism in males is defined by the body’s failure to produce sufficient testosterone, sperm, or both, which are normally generated by the testes. Testosterone is the primary male sex hormone, playing a role in growth, development, and maintaining physical and emotional functions throughout life. This hormonal deficiency, often called “low T,” affects an estimated 4 to 5 million men in the United States, with prevalence increasing notably with age. While it can be present from birth, hypogonadism is frequently acquired later in life and is associated with various chronic health issues.
Understanding Hypogonadism and Its Causes
Male hypogonadism is categorized into two main types based on the location of the problem within the endocrine system. Primary hypogonadism, also known as hypergonadotropic hypogonadism, originates from a defect within the testes. In this scenario, the testes are unable to produce adequate testosterone despite receiving high levels of stimulating signals from the brain.
Causes of primary hypogonadism include genetic conditions like Klinefelter syndrome, where an extra X chromosome interferes with testicular development. Acquired causes involve direct damage to the testes from conditions such as mumps orchitis, physical injury, or medical treatments like radiation and chemotherapy. Iron overload from hemochromatosis can also cause testicular failure.
Secondary hypogonadism, or hypogonadotropic hypogonadism, occurs when the testes are functional but do not receive proper hormonal instructions from the brain. The issue lies with the communication centers—the hypothalamus and the pituitary gland—which fail to release sufficient luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to signal the testes.
This type of hypogonadism can be caused by conditions affecting the brain’s signaling centers, such as tumors, head injuries, or inflammatory diseases. Lifestyle and systemic factors also contribute, including severe obesity, type 2 diabetes, chronic opioid use, and high levels of the hormone prolactin.
Recognizing the Physical and Emotional Signs
The symptoms of male hypogonadism often develop gradually, leading many men to mistakenly attribute the changes to normal aging. Sexual and reproductive function is significantly affected, often presenting as a noticeable decrease in libido. Low testosterone levels are also linked to the inability to achieve or maintain an erection, known as erectile dysfunction.
Physical changes are a hallmark of the condition, including a reduction in muscle mass and strength. Men may also experience an increase in body fat, particularly around the abdomen, and a decrease in bone mineral density, which can lead to osteoporosis. Other physical indicators involve a loss of facial and body hair and, in some cases, the development of breast tissue (gynecomastia).
The condition also impacts emotional and cognitive well-being, resulting in low energy and fatigue that does not improve with rest. Many men report experiencing mood disturbances, such as increased irritability, depression, or mood swings. Difficulty focusing, memory issues, and mental fogginess are common cognitive complaints that can affect daily function.
Diagnosis Through Testing
Confirming hypogonadism requires both a clinical assessment of symptoms and biochemical evidence of low testosterone levels. The initial step is a blood test to measure the serum total testosterone concentration. Because of the natural diurnal variation, this sample must be taken in the morning, typically between 8:00 a.m. and 11:00 a.m., when testosterone levels are highest.
A diagnosis is not made based on a single low result; a persistently low level is required, meaning the test must be repeated on at least one additional morning. A total testosterone level below 300 nanograms per deciliter (ng/dL) coupled with relevant symptoms is used as the threshold for diagnosis. If total testosterone is near the low end of the normal range, doctors may also test for Sex Hormone-Binding Globulin (SHBG) to calculate the more precise free or bioavailable testosterone level.
Additional blood work is performed to determine the type of hypogonadism, which guides treatment. Levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are measured to differentiate between primary and secondary causes. High LH and FSH levels indicate primary hypogonadism, as the brain attempts to stimulate the non-responsive testes. Conversely, low or normal LH and FSH levels suggest secondary hypogonadism, confirming the problem lies in the signaling from the brain.
Available Treatment Approaches
The primary therapeutic intervention for men with symptomatic hypogonadism is Testosterone Replacement Therapy (TRT). TRT restores testosterone to a normal range, which helps alleviate associated physical, sexual, and emotional symptoms. The goal is to improve overall quality of life and protect against long-term consequences like bone loss.
Testosterone can be delivered through several methods, with the choice often depending on patient preference and lifestyle.
Delivery Methods
- Intramuscular injections are administered into the muscle every one to two weeks, or in longer-acting formulations given less frequently.
- Topical gels and creams are applied daily to the skin, providing stable absorption but requiring care to prevent transfer to others.
- Transdermal patches are applied daily and deliver a continuous, steady dose of the hormone.
- Testosterone pellets are small implants placed beneath the skin, typically in the hip or buttocks, that slowly release testosterone over three to six months.
Regardless of the delivery method, ongoing monitoring through regular blood tests is necessary to ensure testosterone levels remain within the appropriate range and to check for potential side effects.