A 29-year-old nulligravid woman comes to the office complaining of increasing bilateral nipple discharge that has been staining her bra for the past two months. The patient has not experienced any breast pain, headaches, or changes in eyesight, nor has she felt any breast mass. Three months have passed since her last period, and home pregnancy tests have come back negative. She used to have normal 28-day menstrual periods in the past. The patient is healthy and does not take any drugs. Vital signs are in the expected range. Visual fields are intact by confrontation upon evaluation. On nipple compression, a yellowish fluid can be expressed bilaterally. Neither lymphadenopathy nor breast lumps exist. An examination of the pelvis reveals no abnormality. Testing of serum beta-hCG is negative. Brain imaging shows a 0.6-cm pituitary mass. Pharmacotherapeutic treatment is begun, and on a follow-up visit the patient reports that her symptoms are improving. Which of the following is the most likely mechanism of action of this medication?

Question

A 29-year-old nulligravid woman comes to the office complaining of increasing bilateral nipple discharge that has been staining her bra for the past two months. The patient has not experienced any breast pain, headaches, or changes in eyesight, nor has she felt any breast mass. Three months have passed since her last period, and home pregnancy tests have come back negative. She used to have normal 28-day menstrual periods in the past. The patient is healthy and does not take any drugs. Vital signs are in the expected range. Visual fields are intact by confrontation upon evaluation. On nipple compression, a yellowish fluid can be expressed bilaterally. Neither lymphadenopathy nor breast lumps exist. An examination of the pelvis reveals no abnormality. Testing of serum beta-hCG is negative.   Brain imaging shows a 0.6-cm pituitary mass.  Pharmacotherapeutic treatment is begun, and on a follow-up visit the patient reports that her symptoms are improving.  Which of the following is the most likely mechanism of action of this medication?

Quizplus · Accepted Answer

Eductional Objective: Galactorrhea is the term for abnormal breast milk secretion that is not related to pregnancy or breastfeeding. Overproduction of prolactin, which directly increases milk secretion in the breasts, is the most frequent cause. Galactorrhea is frequently brought on by pituitary lactotroph adenomas (prolactinomas), which can result in extremely high prolactin levels.
Prolactin is largely under negative regulation by hypothalamic dopaminergic neurons via the pituitary stalk, in contrast to other pituitary hormones, which are under positive regulation by hormones released from the hypothalamus. Dopamine agonists (such cabergoline and bromocriptine), which have a tonic inhibitory effect on prolactin release, can be used to treat hyperprolactinemia. Dopamine agonist therapy reduces adenoma size, suppresses prolactin production, and, in patients with small (<1 cm, as in this patient) prolactinomas and no mass-effect symptoms (eg, headache, visual field defects), can often induce a prolonged clinical response

A 29-Year-Old Nulligravid Woman Comes to the Office Complaining of Increasing