Plasma prolactin activity in inappropriate lactation

Area of Science:

• Endocrinology
• Reproductive Biology
• Molecular Endocrinology

Background:

• Inappropriate lactation, or galactorrhoea, can be associated with pituitary tumors or other endocrine disorders.
• The role of specific pituitary hormones in human galactorrhoea requires further elucidation.
• Distinguishing prolactin from growth hormone in patient plasma is crucial for accurate diagnosis.

Purpose of the Study:

• To determine if prolactin is present in the plasma of patients experiencing inappropriate lactation.
• To investigate the distinctness of prolactin from growth hormone in these patients.
• To explore the relationship between plasma prolactin levels and pituitary status or therapeutic interventions.

Main Methods:

• A bioassay utilizing rabbit mammary tissue's lactogenic response was employed.
• Plasma samples from patients with inappropriate lactation, pituitary tumors, hypothyroidism, and other conditions were analyzed.
• Plasma prolactin levels were monitored during oral glucose tolerance tests in a subset of patients.

Main Results:

• Prolactin, distinct from growth hormone, was detected in the plasma of both male and female patients with inappropriate lactation.
• Elevated prolactin was found in patients with pituitary tumors, primary hypothyroidism with galactorrhoea, and during chlorpromazine therapy.
• Plasma prolactin levels did not change in patients with pituitary tumors but were suppressed in those with normal pituitary fossae during glucose tolerance tests.

Conclusions:

• Prolactin is confirmed as a distinct pituitary hormone in humans, analogous to its role in animals.
• The findings strongly suggest that prolactin is etiologically related to states of inappropriate lactation.
• This research provides evidence for prolactin's central role in the pathophysiology of galactorrhoea.