Serum Prolactin

Function

Prolactin is a hormone produced by the anterior pituitary gland in the brain. Its primary biological role is to stimulate and maintain lactation (breast milk production) in women after childbirth. However, it also plays a role in reproductive health, immune regulation, and metabolic homeostasis in both men and women. In non-pregnant individuals, prolactin levels are usually kept low by dopamine, a brain chemical that inhibits prolactin secretion.

Why it is Ordered

Clinicians order a prolactin test for several reasons:

• In Women: To investigate unexplained nipple discharge (galactorrhea), irregular menstrual cycles (amenorrhea), or infertility.
• In Men: To evaluate decreased libido, erectile dysfunction, or gynecomastia (breast tissue enlargement).
• Both Sexes: To screen for a pituitary tumor called a prolactinoma, which can cause vision problems and headaches due to its location near the optic nerve.
• Monitoring: To track the effectiveness of dopamine agonist medications.

Associated Conditions

• Prolactinoma: A benign tumor of the pituitary gland that overproduces prolactin.
• Hyperprolactinemia: High levels that can interfere with the production of estrogen and testosterone, leading to bone loss or sexual dysfunction.
• Hypothyroidism: Low thyroid hormone levels can trigger an increase in Thyroid-Releasing Hormone (TRH), which also stimulates prolactin release.
• Polycystic Ovary Syndrome (PCOS): Sometimes associated with mild prolactin elevations.
• Kidney or Liver Disease: Reduced clearance of the hormone can lead to elevated levels.