Hyperprolactinemia is an abnormal elevation in the serum prolactin level, from either physiologic or pathologic influences of the lactotroph cells of the pituitary gland.
- Predominant age: reproductive age
- Predominant sex: female (70%) > male (30%)
- More readily detected in females because a slight elevation in prolactin causes changes in menstruation and galactorrhea; men present with headache, visual disturbances, and erectile dysfunction (1)
- Adenomas in men are typically larger because of delayed onset of symptoms (1).
Etiology and Pathophysiology
- Prolactin, which is produced by lactotrophs in the anterior pituitary, is regulated by:
- Inhibitory factors, primarily dopamine, are produced in the hypothalamus and delivered via the hypothalamic-pituitary vessels in the pituitary stalk.
- Stimulatory factors, primarily thyrotropin-releasing hormone (TRH)
- Causes of hyperprolactinemia include the following:
- Pregnancy due to increased estrogen
- Breastfeeding or nipple stimulation
- Stress, including postoperative state
- Dopamine (D2) blockers: prochlorperazine, metoclopramide
- Dopamine depleters: α-methyldopa, reserpine
- Antidepressants: tricyclic antidepressants (TCAs); paroxetine (an SSRI) causes transient hyperprolactinemia—usually resolves in 7 to 10 days
- Verapamil (but no other calcium channel blockers; thought to decrease the hypothalamic synthesis of dopamine)
- Older antipsychotics (category is the most common cause of medication induced): haloperidol, fluphenazine, risperidone (level of elevation with risperidone greater than with other antipsychotics)
- Newer antipsychotics (asenapine, iloperidone, lurasidone) may cause elevation but less than the older antipsychotics (1).
- Hypothyroidism (due to elevated TRH)
- Chest wall conditions such as herpes zoster, trauma, or post-thoracotomy
- Prolactin-secreting adenoma in the anterior pituitary (microadenoma: <1 cm; macroadenoma: >1 cm)
- Pituitary stalk compression/disruption:
- Craniopharyngioma, Rathke cleft cyst
- Meningioma, astrocytoma
- Head trauma
- Infiltrative/inflammatory disorders
- Diminished prolactin clearance (chronic renal failure, cirrhosis, cocaine)
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