Prolactin is a hormone that’s responsible for lactation, certain breast tissue development and milk production. Higher-than-normal levels of prolactin in your blood can cause certain symptoms, such as irregular periods, infertility and erectile dysfunction.

What is Prolactin?

  • Prolactin (also known as lactotropin and PRL) is a hormone that’s responsible for lactation, certain breast tissue development and contributes to hundreds of other bodily processes.

  • Prolactin levels are normally low in people assigned male at birth (AMAB) and non-lactating and non-pregnant people.

  • They’re normally elevated in people who are pregnant or breastfeeding (chestfeeding).

  • Most of your prolactin comes from your pituitary gland.

  • It makes and releases (secretes) the hormone.

  • Your pituitary gland is a small, pea-sized gland located at the base of your brain below your hypothalamus.

  • It’s a part of your endocrine system and is in charge of making many different important hormones, including prolactin.

  • Dopamine (a brain chemical) and estrogen (a hormone) control prolactin production and release from your pituitary gland.

How does Prolactin affect my body?

Prolactin contributes to hundreds of bodily functions, but its two main functions include:

  • The development of mammary glands within breast tissues and milk production.

  • Lactation and breastfeeding (chestfeeding).

Prolactin’s role in mammary gland development and milk production

During pregnancy, the hormones prolactin, estrogen and progesterone stimulate breast tissue development and milk production.

Prolactin promotes the growth of a certain type of breast tissue called mammary alveoli, which are the components of the mammary gland where the production of milk occurs.

Prolactin also stimulates the breast alveolar cells to create milk components, including:

  • Lactose (the carbohydrate component of milk).

  • Casein (the protein component of milk).

  • Lipids (components that provide energy, essential fatty acids and cholesterol).

Prolactin’s role in lactation and breastfeeding (chestfeeding)

  • After delivery of your baby, progesterone levels drop, which increases the number of prolactin receptors on the mammary alveolar cells.

  • This allows for milk secretion through your nipple, commonly known as lactation.

  • After delivery, prolactin levels don’t remain constantly elevated.

  • Prolactin levels will only spike during periods of nipple stimulation through suckling by your baby.

  • As long as your baby maintains suckling, prolactin levels stay elevated.

  • During periods when you’re not breastfeeding, your prolactin levels decrease, and milk production reduces.

  • If a person doesn’t breastfeed their baby, prolactin levels fall to non-pregnant levels after one to two weeks.

What causes Prolactin to increase?

Prolactin levels normally rise during pregnancy and breastfeeding (chestfeeding). They may also rise slightly due to the following situations:

  • Physical stress, such as experiencing pain.

  • Exercise.

  • Eating a meal.

  • Sexual intercourse.

  • Nipple stimulation unrelated to chestfeeding.

  • Injury to your chest area.

  • Epileptic seizures.

What test measures Prolactin levels?

  • A prolactin (PRL) test measures the level of prolactin in your blood.

  • Your healthcare provider may order a prolactin blood test for you if you experience signs and symptoms of elevated prolactin levels and/or to evaluate the function of your pituitary gland.

What are normal Prolactin levels?

Normal value ranges for prolactin levels may vary slightly among different laboratories. Be sure to look at the range of normal values listed on your laboratory report or ask your healthcare provider if you have questions about your results.

In general, the normal values for prolactin include:

  • For people assigned male at birth: Less than 20 ng/mL (nanograms per milliliter).

  • For people assigned female at birth who are not pregnant or chestfeeding: less than 25 ng/mL.

  • For people who are pregnant or chestfeeding: 80 to 400 ng/mL.

What causes abnormally high levels of Prolactin?

Several factors and conditions can cause higher-than-normal levels of prolactin in your blood (hyperprolactinemia), including:

  • Prolactinoma, a pituitary gland tumor (most common cause).

  • Certain medications.

  • Certain health conditions.

  • Other pituitary gland tumors.

What causes abnormally low levels of Prolactin?

  • Your prolactin levels are usually low unless you’re pregnant or breastfeeding (chestfeeding), so the only sign of having lower-than-normal levels of prolactin is a lack of breastmilk production after giving birth.

  • In these cases, hypopituitarism is often the cause.

  • Hypopituitarism is a rare condition in which there’s a lack (deficiency) of one, multiple or all of the hormones your pituitary gland makes.

  • It’s usually caused by abnormal pressure on your pituitary gland or damage to your pituitary gland.

hormones prolactin

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