Hyperprolactinemia
Study guide:
Definitions:
Prolactin is a 198-amino acid protein (23-kd) produced by the lactotroph cells of the anterior pituitary gland. Its main function is to (improve) breast development during pregnancy and to induce lactation. Prolactin also binds to specific receptors in lymphoid cells, gonads, and liver.
Etiology:
1. Prolactinoma:
- Most common etiology of hyperprolactinemia
- prolactin-secreting tumors maybe induced by
estrogens and grow during pregnancy)
2. Medication:
- medications with anti-dopaminergic properties are a common cause of high prolactin levels: antipsychotics (common)
- antidepressants
- antihypertensives
- anti-migraine agents (triptans/ ergotamines),
- bowel motility agents (metoclopramide/domperidone),
- H2-blockers (ranitidine)
- verapamil
- estrogen
3. Pregnancy and breastfeeding
4. Renal failure
5. Spurasellar mass lesion with pituitary stalk compression causing reduced dopamine inhibition of prolactin release
6. Primary hypothyroidism ( because it increases TRH)
7. Decreased clearance due to chronic renal failure or severe liver disease (prolactin is metabolized by both the kidney and liver)
8. Idiopathic
Clinical Presentation:
In women:
1. premenopausal: menstrual irregularities,
-
Oligomenorrhea or amenorrhea, galactorrhea in absence of pregnancy. Prolactin inhibits GNRH. If there is no GNRH, the body cannot release LH and FSH.
-
an ovulation and infertility, decreased libido, dyspareunia, vaginal dryness, risk of osteoporosis,
2. Postmenopausal: parasellar signs and symptoms which are less common than in men
In men:
-
Hypogonadism, decreased libido, infertility, impotence/ erectile dysfunction
-
galactorrhea or gynecomastia
-
parasellar signs and symptoms ( headaches and visual field defects )
( they’re more prevalent in men than in women and this is mainly because the early symptoms in men like impotence are attributed to psychological causes and medical evaluation is delayed, allowing for larger tumor growth)
Diagnosis:
Management:
1. Treat any underlying cause ( i.e primary hypothyroidism, stop medication)
2. If the cause is prolactinoma and the patient is symptomatic, treatment options are:
- Bromocriptine which is a dopamine agonist that diminishes prolactin production and release.
- Cabergoline ( also dopamine agonist) might be better tolerated than bromocriptine
- Continue treatment for at least 2 years.
3. If symptoms progress despite medical therapy, consider surgical intervention. Recurrence rate after surgery is high.
References:
1. Step up to medicine 4th edition
2. Toronto notes 2018
3. Master the Boards USMLE Step 3, 3rd Edition