Hyperprolactinemia, characterized by abnormally high levels of the hormone prolactin in the blood, can impact men’s health. While prolactin is known for its role in milk production in women, elevated levels in men can lead to a range of symptoms and health concerns. Understanding this condition is crucial for proper diagnosis and management, as it affects reproductive function, sexual health, and overall well-being.
Understanding Prolactin and Hyperprolactinemia
Prolactin is a peptide hormone produced primarily by the pituitary gland. While its most well-known function is stimulating milk production in women, prolactin also plays roles in the male body. In men, prolactin contributes to the regulation of testosterone production, supports healthy sperm production, and influences immune system modulation and metabolism. Normal prolactin levels in men are typically less than 20 ng/mL.
Hyperprolactinemia refers to a condition where prolactin levels in the blood exceed this normal range. Its elevation in men can lead to significant health issues. The pituitary gland normally produces and releases prolactin, with its production largely controlled by dopamine, a neurotransmitter that suppresses prolactin release. When this balance is disrupted, prolactin levels can rise, leading to various clinical manifestations.
Recognizing Hyperprolactinemia in Men
Symptoms of elevated prolactin levels in men are often subtle and can develop gradually. A common manifestation is sexual dysfunction, including decreased libido and erectile dysfunction. These symptoms often stem from hyperprolactinemia’s interference with gonadotropin production, which reduces testosterone levels.
Fertility issues are also observed in men with high prolactin, as elevated levels can impair sperm production and quality. Some men may experience gynecomastia (enlargement of breast tissue) or, in rarer instances, galactorrhea (milky discharge from the nipples). Other potential symptoms include excessive fatigue, mood swings, and a loss of muscle mass or body hair. In cases where a pituitary tumor is involved, men might also experience headaches or visual disturbances due to the tumor pressing on nearby structures.
Causes of Elevated Prolactin Levels
Elevated prolactin levels in men can stem from physiological responses, medical conditions, or medications. Physiological causes, often temporary, include stress, strenuous exercise, nipple stimulation, and sleep disturbances.
Pharmacological causes are a frequent reason for hyperprolactinemia, as certain medications interfere with dopamine’s ability to suppress prolactin. These include some antipsychotic drugs (e.g., risperidone, haloperidol), antidepressants (e.g., tricyclic antidepressants, SSRIs), certain blood pressure medications, opioid pain relievers, H2 antihistamines, and antiemetics. Prolactin levels typically return to normal after stopping the causative medication, though this should only be done under medical guidance.
Pathological causes are more persistent. The most common is a prolactinoma, a noncancerous pituitary tumor that produces excess prolactin. Other conditions leading to high prolactin include hypothyroidism, chronic kidney disease, liver disease, chest wall injuries, and other pituitary disorders.
Diagnosis and Management Strategies
Diagnosis of hyperprolactinemia typically begins with a blood test to measure serum prolactin levels. A fasting blood sample is generally preferred, as prolactin levels can fluctuate with sleep and stress. A prolactin level over 25 mcg/L is often considered elevated, though mild elevations may not always be clinically significant. If initial results show high prolactin, further tests are usually conducted to determine the underlying cause.
Imaging studies are often necessary, particularly if a prolactinoma is suspected. Magnetic Resonance Imaging (MRI) of the pituitary gland is the preferred imaging method to detect tumors. Additional blood tests may be performed to check thyroid function, kidney function, and other hormone levels like testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH).
Treatment for hyperprolactinemia is tailored to address the specific underlying cause. For prolactinomas, dopamine agonists such as cabergoline and bromocriptine are generally the first-line treatment. These medications work by mimicking dopamine, which helps to suppress prolactin production and can shrink the tumor. Cabergoline is often favored due to its greater effectiveness and fewer side effects compared to bromocriptine.
In cases where medication is ineffective, or if the tumor is very large, surgical removal of the tumor (transsphenoidal resection) may be considered. Radiation therapy is typically a third-line option for resistant or malignant prolactinomas. If the cause is a medication, adjusting or discontinuing the drug might be recommended under medical supervision. For other underlying conditions like hypothyroidism or kidney disease, managing these conditions can help normalize prolactin levels.