Endocrinologists treat low testosterone, medically known as hypogonadism. They are hormone specialists focusing on the endocrine system, the network of glands that produces and secretes hormones to regulate body functions, including testosterone production. Since hypogonadism is fundamentally a hormonal imbalance, an endocrinologist is uniquely qualified to diagnose the underlying cause and manage treatment. Their comprehensive training in the intricate feedback loops between the brain and the testes makes them experts in addressing this specific hormonal disorder.
Defining Low Testosterone and Its Causes
Low testosterone, or male hypogonadism, is a condition where the testes do not produce enough of the sex hormone testosterone, or the body has difficulty using it. This hormone is responsible for maintaining muscle mass, bone density, sexual function, and a general sense of well-being. When levels drop below the accepted threshold—often cited as below 300 nanograms per deciliter (ng/dL)—men may experience several noticeable changes.
Common symptoms include persistent fatigue, reduced sex drive, difficulty achieving or maintaining an erection, and changes in mood, such as increased irritability or depression. Over time, the condition can also lead to a decrease in muscle mass, an increase in body fat, and a loss of bone density, which may increase the risk of fractures.
The causes of hypogonadism are broadly categorized into two types: primary and secondary. Primary hypogonadism originates from a problem within the testes themselves, meaning they cannot produce enough testosterone. Causes may include genetic conditions like Klinefelter syndrome, physical injury, infection (such as mumps), or past exposure to chemotherapy or radiation. Secondary hypogonadism is a signaling problem where the testes are functional, but the brain’s regulatory centers—the hypothalamus and pituitary gland—fail to send the proper hormonal signals. This communication breakdown can be caused by conditions affecting the pituitary gland, certain medications, or chronic illnesses like type 2 diabetes and obesity.
The Endocrinologist’s Role in Diagnosis and Management
Endocrinologists are the preferred specialists for low testosterone because their training covers the entire endocrine axis, allowing them to thoroughly investigate both primary and secondary causes. They are experts in the complex hormonal feedback loop involving the hypothalamus, the pituitary gland, and the testes. This holistic view ensures that potentially serious underlying issues are addressed, not just the symptoms.
Diagnosis begins with confirming the low testosterone level, requiring at least two separate blood tests for total testosterone, typically drawn in the morning. Further blood work measures luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to determine the type of hypogonadism. If LH and FSH levels are high, it indicates primary hypogonadism (testicular failure), as the brain attempts to stimulate the non-responsive testes.
If LH and FSH are low or normal alongside low testosterone, it suggests secondary hypogonadism, pointing to a problem in the pituitary or hypothalamus. The endocrinologist may investigate further with additional tests, such as prolactin levels, and potentially magnetic resonance imaging (MRI) of the pituitary gland to rule out a tumor. Management extends to long-term monitoring, tracking blood cell count (hematocrit), prostate-specific antigen (PSA) levels, and cholesterol to ensure the therapy is safe and effective.
Approaches to Testosterone Replacement Therapy (TRT)
Once symptomatic hypogonadism is confirmed, the endocrinologist discusses the various methods of Testosterone Replacement Therapy (TRT) to restore testosterone levels to the mid-normal range. The choice of delivery system is highly personalized, taking into account the patient’s lifestyle and need for stable hormone levels.
The primary TRT delivery methods include:
- Injections: Intramuscular injections (e.g., testosterone cypionate or enanthate) are administered every one to four weeks. They are effective and cost-efficient, but can cause a peak and trough effect, leading to temporary fluctuations in mood and energy.
- Topical Gels and Creams: Applied daily to the skin, these offer a non-invasive route and consistent hormone levels. A drawback is the risk of transferring testosterone to a partner or child through close physical contact, requiring careful hygiene.
- Patches: These transdermal options offer steady daily delivery, though they may cause skin irritation or adherence issues.
- Pellets: Small implants inserted under the skin release testosterone slowly over three to six months. This provides long-term convenience and stable levels but limits flexibility for immediate dosage adjustments.
The endocrinologist guides the patient through these options, weighing hormone stability, potential side effects, and personal comfort to select the most appropriate treatment plan.
When to Consult a Urologist or Primary Care Physician
While endocrinologists are the hormone experts, other medical professionals also play a role in the management of low testosterone. A primary care physician (PCP) is often the first point of contact for a patient experiencing symptoms like fatigue or low libido. The PCP can order the initial screening blood tests for total testosterone and manage straightforward cases, especially if symptoms are mild or the cause is clearly related to lifestyle factors.
A referral to a specialist becomes necessary if the cause is complex, the patient does not respond to initial therapy, or a pituitary or testicular issue is suspected. Urologists specialize in the male reproductive and urinary systems and are often consulted when fertility is a concern. Standard TRT can suppress sperm production, so a urologist or endocrinologist can discuss fertility-sparing treatment options, such as human chorionic gonadotropin (hCG) or selective estrogen receptor modulators (SERMs). Urologists also manage low testosterone connected to structural issues, like testicular injury, or co-occurring with conditions such as erectile dysfunction.