Is idiopathic hyperprolactinemia a transitional stage toward prolactinoma?

Area of Science:

• Endocrinology
• Reproductive Medicine
• Hormone Physiology

Background:

• Hyperprolactinemia, characterized by elevated prolactin (PRL) levels, affects women's reproductive health.
• Understanding the spectrum of lactotroph activity is crucial for accurate diagnosis and treatment.
• Idiopathic hyperprolactinemia presents diagnostic challenges due to its heterogeneous nature.

Purpose of the Study:

• To investigate the relationship between basal prolactin levels and hormonal responses to stimuli in women.
• To delineate the spectrum of lactotroph function in regularly menstruating women and those with hyperprolactinemia.
• To clarify the diagnostic utility of PRL and TSH responses in managing hyperprolactinemia.

Main Methods:

• Studied basal prolactin (PRL) levels over five days in 75 regularly menstruating women and 44 with hyperprolactinemia.
• Assessed PRL responses to thyrotropin-releasing hormone (TRH) and domperidone.
• Measured thyroid-stimulating hormone (TSH) responses to domperidone.

Main Results:

• Hormonal responses to TRH and domperidone correlated continuously with basal PRL levels across the entire sample.
• Diagnostic information from PRL responses to TRH and domperidone is limited in macroprolactinemia cases.
• A continuous spectrum of lactotroph activity was observed, from normal secretion to prolactinomas.

Conclusions:

• Hyperprolactinemia exists on a continuous spectrum of lactotroph activity, not distinct categories.
• Idiopathic hyperprolactinemia is heterogeneous, encompassing intermediate hypersecretors, macroprolactinemia, and undiagnosed prolactinomas.
• Basal PRL levels are key, with stimuli offering limited additional diagnostic value in specific hyperprolactinemia subtypes.