Understanding Hyperprolactinaemia: Insights and Implications

Hyperprolactinaemia is a condition characterized by elevated levels of prolactin (PRL) in the blood, often leading to a range of symptoms and complications. It primarily affects men and post-menopausal women, who tend to present later in the course of the disease when larger macroadenomas may be present. Patients may experience symptoms related to space-occupying lesions, such as headaches or visual disturbances, stemming from the pituitary gland's abnormal growth.

In men, hyperprolactinaemia can manifest as gynaecomastia, which is the enlargement of breast tissue, or signs of secondary hypogonadism, such as reduced libido or erectile dysfunction. These symptoms arise due to the hormone's suppressive effects on luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are essential for testosterone production. Recognizing these signs is crucial for early diagnosis and management.

The diagnosis of hyperprolactinaemia is challenging and requires careful evaluation, including multiple blood tests. A single venous blood sample may yield false positives due to stress-induced elevation of PRL levels. Additionally, some assays may detect macroprolactin—an inactive form of the hormone—which can mislead clinicians into diagnosing hyperprolactinaemia incorrectly. Specialized laboratory methods are available to differentiate between the active and inactive forms, ensuring accurate results.

Excluding pregnancy is a critical step in the diagnostic process, as elevated PRL can also occur during gestation. When PRL levels are consistently above the normal range (approximately 500 mU/L or 25 ng/mL), further investigation is warranted to identify underlying causes. The severity of PRL elevation often provides clues regarding the nature of the pathology, distinguishing between microprolactinomas and macroprolactinomas.

Prolactin secretion is influenced by various factors, including stress, sleep, and suckling stimuli. While dopamine is the primary inhibitory regulator of PRL release, other hormones like thyrotrophin-releasing hormone (TRH) can stimulate its production. Understanding these regulatory mechanisms is essential for grasping how hyperprolactinaemia develops and identifying effective treatment strategies tailored to individual patients.

The implications of hyperprolactinaemia extend beyond reproductive health, potentially affecting metabolic functions and immune responses. As research continues to uncover the complexities of this condition, increased awareness and understanding can lead to more effective diagnostic and therapeutic approaches, ultimately improving patient outcomes.