Description

Hyperprolactinemia is an abnormal elevation in the serum prolactin level, from either physiologic or pathologic influences of the lactotroph cells of the pituitary gland.

Epidemiology

Prevalence

• 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:
  • Physiologic
  • Pregnancy due to increased estrogen
  • Breastfeeding or nipple stimulation
  • Stress, including postoperative state
  • Medications: Concentrations are typically in the 20 to 100 ng/mL range (2)[A].
    • 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
    • Metastases
    • Head trauma
    • Infiltrative/inflammatory disorders
  • Diminished prolactin clearance (chronic renal failure, cirrhosis, cocaine)
  • Idiopathic hyperprolactinemia—a substantial number of cases where the serum levels are between 20 and 100 ng/mL and the cause cannot be found (3)[A]