Low testosterone occurs when the body does not produce enough of the hormone to maintain normal function. This hormonal imbalance can lead to a range of symptoms, including fatigue, decreased libido, and loss of muscle mass. The primary specialists who address this condition are endocrinologists, who manage disorders of the endocrine system. They manage low testosterone because it represents a dysfunction in the body’s complex hormonal signaling network.
Defining the Endocrinologist’s Expertise
An endocrinologist is a physician who specializes in the diagnosis and treatment of disorders affecting hormones, glands, and the metabolic system. Their training centers on the intricate feedback loops that govern hormone production throughout the body. This specialization is highly relevant to low testosterone because the condition is rarely a simple deficiency.
The cause of hypogonadism is classified as either primary or secondary. Primary hypogonadism involves a problem directly within the testicles. Secondary hypogonadism is caused by a failure in the communication system between the brain—specifically the hypothalamus and pituitary gland—and the testicles. The pituitary gland releases Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), which signal the testicles to produce testosterone.
Endocrinologists focus on identifying the precise location of this hormonal breakdown, distinguishing between testicular failure and a signaling issue originating in the brain. Their expertise allows them to evaluate the entire hormonal picture, often revealing underlying issues like thyroid problems or pituitary tumors that may be contributing to the low testosterone. This systemic approach goes beyond merely prescribing testosterone.
The Diagnostic Process for Low Testosterone
Diagnosis of low testosterone requires both clinical symptoms and specific laboratory confirmation. Diagnosis is based on symptoms paired with consistently low testosterone levels measured on at least two separate occasions. The initial blood test must measure the total testosterone level, which represents the total amount of the hormone circulating in the blood.
Due to testosterone’s natural circadian rhythm, where levels peak in the morning and decline throughout the day, blood samples must be collected in the early morning, typically between 7:00 AM and 10:00 AM. Testing later in the day, especially in younger men, can produce a falsely low reading. If the total testosterone level is low, additional tests are often ordered, including free testosterone, which is the biologically active hormone unbound to proteins, and the pituitary hormones LH and FSH.
Analyzing LH and FSH levels helps the endocrinologist determine the cause of the deficiency. High levels of LH and FSH suggest primary hypogonadism, indicating the brain is signaling the testicles, but they are failing to respond. Conversely, low or inappropriately normal LH and FSH levels point toward secondary hypogonadism, meaning the brain is not sending a proper signal to the testicles.
Navigating Testosterone Replacement Therapy Options
Once a diagnosis is confirmed, the endocrinologist will discuss Testosterone Replacement Therapy (TRT) options, which come in several delivery forms.
Injections
Intramuscular injections are a popular and cost-effective method, typically involving testosterone cypionate or enanthate. These injections are usually administered weekly or biweekly. This provides a large dose that results in fluctuating hormone levels, peaking shortly after injection and troughing before the next dose.
Transdermal Methods
Transdermal methods, such as gels and patches, offer a more consistent, physiologic release of the hormone. Gels are applied daily to the skin of the shoulders or abdomen, allowing for steady absorption. A primary concern with gels is the risk of transference to a partner or child through skin contact, which necessitates caution after application. Patches are also applied daily, but they may cause local skin irritation.
Subcutaneous Pellets
The subcutaneous pellet system involves inserting rice-sized pellets of testosterone under the skin, usually in the hip or buttocks area, during a minor in-office procedure. These pellets gradually release testosterone over three to six months, offering convenience and stable hormone levels. However, the dosage is not easily adjusted once implanted, and they are typically the most expensive option.
Oral Formulations
Finally, newer oral formulations exist that bypass liver metabolism. These are taken twice daily with food.
When Other Specialists Get Involved
While the endocrinologist is the specialist for complex hormonal management, other medical professionals contribute to comprehensive care. Primary Care Physicians (PCPs) are often the first point of contact and may manage straightforward cases of low testosterone. A PCP can order the initial blood tests and prescribe TRT, referring to a specialist if the cause is unclear or if the patient has complex co-existing conditions.
Urologists focus on the male reproductive and urinary systems. They become particularly involved when low testosterone is associated with issues directly related to the reproductive tract, such as erectile dysfunction, infertility, or prostate health concerns. In many cases, the two specialists may collaborate, with the endocrinologist managing the systemic hormone balance and the urologist addressing localized reproductive or urinary symptoms.