Hyperprolactinemia

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Description

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

Epidemiology

Incidence

In the general population, hyperprolactinemia affects 5 to 20 people per 100,000 per year.

Prevalence

  • Predominant age: reproductive age
  • Predominant sex: female (70%) > male (30%)
  • More readily detected in females because a slight elevation in PRL 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

  • PRL, 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 25 to 100 ng/mL range (2)[A].
        • Dopamine (D2) blockers: prochlorperazine, metoclopramide
        • Dopamine depleting: α-methyldopa, reserpine
        • Antidepressants: tricyclic antidepressants (TCAs); paroxetine (an SSRI) causes transient hyperprolactinemia—usually resolves in 7 to 10 days
        • Gastric motility drugs: metoclopramide and domperidone
        • 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).
    • Pathologic
      • Hypothyroidism (due to elevated TRH)
      • Chest wall conditions such as herpes zoster, trauma, or postthoracotomy
      • PRL-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 PRL clearance (chronic renal failure, cirrhosis, cocaine)
    • Idiopathic hyperprolactinemia—a substantial number of cases where the serum levels are between 20 and 100 ng/mL the cause cannot be found (3)[A].

Genetics

Unknown

Risk Factors

See causes in “Etiology and Pathophysiology” section.

General Prevention

Avoid offending medications.

Commonly Associated Conditions

  • Infertility
  • Osteoporosis
  • Amenorrhea
  • Gynecomastia

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