Prolactin

Prolactin is a peptide hormone produced primarily by the anterior pituitary gland. While best known for its role in lactation, it also influences immune regulation, metabolism, reproductive health, and behavior.

Functions

• In females:

  • Stimulates milk production (lactogenesis) after childbirth

  • Regulates menstrual cycles and supports fertility

• In males:

  • Modulates testosterone production and supports sperm development

• Additional roles:

  • Modulates immune responses

  • Influences metabolism, fluid balance, and stress adaptation

Normal Ranges (ng/mL)

• Females: 4.8 – 23.3

• Males: 4.0 – 15.2

Clinical Significance

• Hyperprolactinemia (Elevated Prolactin)

  • Causes:

    • Prolactin-secreting pituitary adenoma (prolactinoma)

    • Hypothyroidism

    • Chronic kidney disease

    • Certain medications (e.g., antipsychotics, antiemetics)

  • Symptoms in women:

    • Galactorrhea (milk discharge unrelated to breastfeeding)

    • Oligomenorrhea or amenorrhea (irregular or absent periods)

    • Infertility

  • Symptoms in men:

    • Decreased libido

    • Erectile dysfunction

    • Rarely galactorrhea

• Hypoprolactinemia (Low Prolactin)

  • Causes:

    • Pituitary insufficiency

    • Excessive stress

  • Symptoms in women:

    • Inadequate breast milk production after delivery

    • Irregular menstrual cycles

    • Infertility

  • Symptoms in men:

    • Generally fewer clear signs, may include reduced libido and mild infertility

Diagnosis

• Blood test measuring serum prolactin, ideally drawn in the early morning after minimal stress.

• If elevated without clear cause, further evaluation may include:

  • MRI or CT scan of the pituitary gland

  • Thyroid function tests

  • Renal function tests

Frequently Asked Questions

1. What causes high prolactin levels?

   • Pituitary tumors (prolactinomas), untreated hypothyroidism, kidney disease, and certain medications.

2. How is prolactin tested?

   • Via a simple blood draw; fasting is not typically required, but avoid stress before the test.

3. How is hyperprolactinemia treated?

   • Dopamine agonists (e.g., bromocriptine), treating underlying hypothyroidism, or surgery for large adenomas.

4. Can stress affect prolactin levels?

   • Yes, acute physical or emotional stress can temporarily raise prolactin.

5. What are the effects of low prolactin?

   • Difficulty with postpartum milk production and potential menstrual irregularities in women; mild reproductive impact in men.