Prolactin (Serum)
Prolactin rises progressively during pregnancy due to estrogen-driven pituitary lactotroph hyperplasia. Levels peak near term and correlate with postpartum lactation potential.
| Units | Nonpregnant Female | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| ng/mL | 0 – 20 | 36 – 213 | 110 – 330 | 137 – 372 |
| µg/L | 0 – 20 | 36 – 213 | 110 – 330 | 137 – 372 |
| pmol/L | 0 – 859 | 1,565 – 9,261 | 4,783 – 14,347 | 5,957 – 16,174 |
Pregnancy Physiology
- Prolactin is produced by anterior pituitary lactotrophs, which markedly hyper-proliferate during pregnancy.
- Rising maternal estrogen stimulates increased prolactin synthesis.
- Essential for mammary gland development and preparation for lactation.
- Despite very high prolactin levels, lactogenesis is inhibited by progesterone until after delivery.
- After birth, suckling suppresses dopamine and sustains prolactin secretion.
Causes of LOW Prolactin
- Pituitary ischemia (Sheehan syndrome)
- Hypopituitarism
- Dopamine agonist therapy (bromocriptine, cabergoline)
- Levodopa and dopamine-enhancing medications
- Severe postpartum hemorrhage
- Autoimmune hypophysitis
Causes of HIGH Prolactin
- Normal pregnancy (most common physiologic cause)
- Prolactinoma or pituitary adenoma
- Hypothyroidism (TRH-mediated stimulation)
- Chest wall stimulation or trauma
- Stress, exercise, and sleep
- Medications (antipsychotics, SSRIs, metoclopramide, methyldopa, estrogen)
- Renal failure (reduced clearance)
References
- Kratz A, Ferraro M, Sluss PM, Lewandrowski KB. N Engl J Med. 2004;351:1548–1563.
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Obstet Gynecol. 2009;114:1326–1331.