Prolactin is a hormone that is best known for allowing pregnant and breastfeeding women to produce milk.  It also plays a role in many other functions throughout the body in both males and females.

What is Prolactin

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Prolactin is a peptide hormone made by the pituitary gland and various other parts of the body. It is also referred to as the luteotropic hormone (luteotropin) and PRL. Prolactin is encoded by the PRL gene (R).

Primarily, prolactin is responsible for the stimulation of milk production in women (lactogenesis) (R).

When a woman is pregnant, prolactin levels increase by up to 10-20 times the  normal amount.  The levels return to normal within a few weeks after the mother stops breastfeeding.

Despite what its name suggests, prolactin does much more than only promote lactation. It is found in men as well and is influential in over 300 separate processes.  It is recognized as a multipurpose hormone with one of the widest ranges of physiological actions of any hormone (R).

Prolactin is important for water/salt regulation, metabolism, reproductive behavior, the immune system, hormones, and the brain (R).

Main Functions of Prolactin

1) Prolactin Helps Create Breast Milk

Milk production occurs after birth by allowing prolactin levels to remain elevated while progesterone and estrogen undergo an abrupt drop as they are rapidly cleared in 3-4 days after birth from the body. Estradiol acts at the hypothalamic level to increase prolactin secretion (R).

In the process of milk production, prolactin, along with cortisol and insulin, act together to stimulate genes that encode milk proteins.

Together, they stimulate the uptake of various amino acids and glucose, and the synthesis of the milk proteins (casein), fats, sugar (lactose), spermidine, and phospholipids. Nonpregnant levels of prolactin are sufficient to maintain milk production (R1,R2,R3).

In breastfeeding mothers, prolactin is mainly secreted in response to stimulation of the nipples and breast by a suckling infant.  The suckling by the baby blocks the secretion of hypothalamic dopamine (which normally inhibits prolactin). This results in a sharp rise in prolactin concentrations in the blood, followed by a prompt fall when feeding stops (R).

The suckling activates mechanoreceptors in and around the nipple and these signals are carried by nerve fibers through the spinal cord to the hypothalamus (R).

High prolactin can cause bone loss in order to export calcium to the breast milk (R, R, R, R, R).

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2) Prolactin Plays a Role in Breast Development

Prolactin is merely a player in an orchestra of hormones and growth factors that supports breast development (R).

Normal breast development requires prolactin, estrogen, progesterone, growth hormone, insulin, cortisolthyroid and parathyroid hormoneIGF-1, and EGF.  All of these together result in a functional gland (R).

Increased concentrations of prolactin in the blood during pregnancy cause enlargement of the mammary glands in order to prepare for milk production(R).

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3) Prolactin Makes You More Nurturing and Influences Sexual Desire

In humans, high prolactin levels are associated with nurturing and parenting behaviors, as well psychosomatic reactions including false pregnancy (R).

Prolactin may have a role in paternal care as well (in fish and birds).  In species where the male plays some role in the rearing of the offspring (rats), including humans, studies have found an association between prolactin and paternal care (RR).

In women, prolactin can both increase or decrease sexual desire, and this depends on various factors.  In men, prolactin suppresses sexual behavior in rats (R).

4) Prolactin Helps Fetal Brain Development

Prolactin stimulates the growth, development, and metabolism of the fetus.  It also stimulates the formation of myelin coatings on axons in the brain (R).

Prolactin promotes neurogenesis in the mother and her fetus, immune tolerance of the fetus during pregnancy and contributes to the development of the fetal lungs (R).

5) Prolactin Helps Fertility (sometimes)

Since prolactin increases progesterone, it helps to sustain pregnancies (RR).

However, unusually high levels during pregnancy are associated with spontaneous abortion (R, R).

Thus, high prolactin concentrations during breast feeding reduce fertility, protecting women from a premature pregnancy (R).

At lower levels, prolactin can contribute to male fertility in mice (R), but high prolactin causes infertility in males.  It can also cause low testosterone, a lack of sexual desire, or erectile dysfunction (R).

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Prolactin Affects Other Hormones

Elevated levels of prolactin decrease the levels of estrogen in women and testosterone in men. The effects of altered levels of prolactin on sex hormones are much more profound in women, substantially increasing or decreasing estrogen levels (R).

High prolactin concentrations inhibit secretion of GnRH, thereby decreasing luteinizing hormone and follicle-stimulating hormone (R).

Normal levels of prolactin in males enhance testosterone secretion and the creation of sperm (R).

Prolactin decreases hepcidin, which can increase blood iron levels (R).

Prolactin indirectly leads to the release Parathyroid hormone-related peptide (PTHrP) (via increasing serotonin synthesis in breasts), causing bone loss (R).

Normal Levels of Prolactin

The upper threshold of normal prolactin is about 25 µg/L for women and 20 µg/L for men. Prolactin levels below 3 µg/L in women and 5 µg/L in men are considered too low. Prolactin levels may be checked as part of a sex hormone workup since elevated prolactin secretion can suppress the secretion of other hormones like FSH, GnRH, and sex hormones (R).

Ideal levels of prolactin for men are probably between 5-10 µg/L.

Prolactin level blood tests are most accurate if conducted during the midmorning and not after stress, breast stimulation, physical examination, or other prolactin-increasing stimuli. In addition, elevated levels of prolactin should always be rechecked due to the variability of secretion and inaccurate test readings (R1,R2).

Prolactin levels rise starting one hour after a person falls asleep until peak amounts are reached between 5:00 and 7:00 AM.  The lowest levels occur during the midmorning after waking (R).

Normal Prolactin Levels in the Blood:

Nonpregnant women 4-23 nanograms per milliliter (ng/mL) or 4-23 micrograms per liter (mcg/L)
Men 3-15 ng/mL or 3-15 mcg/L
Pregnant women 34-386 ng/mL or 34-386 mcg/L
Children 3.2-20 ng/mL or 3.2-20 mcg/L

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High Levels of Prolactin

Higher levels of prolactin are found in pregnancy and breast feeding (R).

High levels of prolactin in a woman may cause:

  • Abnormal nipple discharge
  • Infertility/Difficulty getting pregnant
  • Low estrogen and progesterone levels (R)
  • Difficulty getting a period
  • Tiredness
  • Headaches
  • Nausea
  • Dizziness
  • Vision problems

High prolactin in males can cause (R):

  • Infertility
  • Low testosterone
  • Low sexual desire
  • Erectile dysfunction

A small benign tumor (microprolactinoma) is found in the pituitary of over one-third of women with high levels of prolactin (R).

Low Levels of Prolactin

Low prolactin is associated with ovary dysfunction in women.

In men low prolactin is associated with (R):

  • Low testosterone
  • Erectile dysfunction
  • Premature ejaculation
  • Low sperm count
  • Reduced sperm motility
  • Decreased function of seminal vesicles

In one study on low prolactin in men, normal sperm function was restored when prolactin levels were raised back to their correct values (R).

In mice without prolactin receptors, the hair cycle is disrupted such that shedding occurred earlier and there was a reduced duration of the telogen phase (R).

What Increases Prolactin

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Prolactin levels are the highest during sleep, shortly after you wake up, and during times of physical or emotional stress.

In a study on female volunteers under hypnosis, prolactin surges resulted from rage or humiliating experiences, but not from the fantasy of nursing.  Interestingly, compared to single males, fathers generally have higher prolactin concentrations (R).

The most consistent stimulus for prolactin secretion in males is stress (R).

Production of the prolactin-receptor in the brain increases with age, exposure to estrogens, elevation in prolactin levels, and by contact with babies (R).

Conditions with increased prolactin:

  • Pregnancy
  • Stress
  • Depression
  • Ovulation
  • Trauma
  • Surgery
  • Tumors of the pituitary gland (prolactinomas)
  • Hypothyroidism
  • Kidney disease
  • Liver disease
  • Seizures
  • Antipsychotics (via blocking DRD2 receptors) (R).
  • Some drugs and medications

Activities that increase prolactin:

Hormones that increase prolactin:

Other:

  • Activating the serotonin receptors 5HT2A and 5HT2C

What Decreases Prolactin

Low prolactin can be caused by (R,R):

Hormones that decrease prolactin:

Supplements that decrease prolactin:

Dopamine

The primary Prolactin Inhibiting Factor (PIF) is the neurotransmitter dopamine.  When prolactin is produced, the secretion of dopamine increases as well, which then restricts prolactin production.

Treatment with dopamine or compounds that activate dopamine receptors suppresses prolactin secretion (R).

Estrogen & Progesterone

Studies have shown that increased levels of estrogen correlate to higher amounts of prolactin secretion.  This is confirmed by the fact that women have higher levels of prolactin in their blood during stages of pregnancy and their reproductive cycle when estrogen levels are higher too (R).

Estrogen enhances the growth of prolactin-producing cells, stimulates prolactin production directly, and suppresses the production of dopamine (R).

Progesterone increases and decreases prolactin, depending on the area of the body (R).

Prolactin: The Bad

Many of the metabolic and immune functions of prolactin can be observed in males, but for some of effects prolactin might not be high enough to be significant (R).

1) Prolactin is an Immune Stimulant

Prolactin affects a large number of cytokine receptors (R) and acts in a cytokine-like manner, increasing the production of many immune system cells (R).

Prolactin is mostly an immune stimulant. The hormone plays a role in autoimmune diseases.

Some types of lymphocytes secrete prolactin and this allows for production of more lymphocytes (R,R,R).  Lymphocytic prolactin plays a role in skin graft rejection (R).

Immune responses (B cell, T cell) in organisms are enhanced by prolactin (R).

Prolactin increases cytokine secretion and inhibits the suppressor effect of regulatory T (Treg) cells in healthy individuals (R).

Treg cells help create tolerance and an anti-inflammatory environment.

Prolactin stimulates T effector cells (not good for autoimmune) and increases IFNy secretion, which encourages an inflammatory environment and Treg cell malfunction (R).

However, prolactin deficiency can cause immunodeficiency (R).

Interestingly, mice without the prolactin gene fail to show significant abnormalities in immune responses.  As a result, prolactin has a modulatory role in several aspects of immune function but is not strictly required for these responses (R).

2) Prolactin Can Cause Autoimmune Disease

Excess prolactin is one of the important factors in the development and course of autoimmune diseases such as (R, R2):

3) Prolactin Can Cause Weight Gain and Hunger

Prolactin receptors are found in fat tissue, liver, pancreas and the brain (R).

In fat tissue, prolactin is essential in fat cell production. It also increases the secretion of leptin and inhibits adiponectin (R).

Prolactin promotes appetite and contributes to the rapid increase in food intake during pregnancy and nursing (R).

In the pancreas, it increases insulin secretion (from glucose) and glucose sensitivity (R). This helps prevent diabetes during pregnancy, but can cause weight gain (R).

Prolactin also induces functional leptin resistance, which would contribute to increased food intake, potentially mediating the well-established leptin resistance of pregnancy (R).

Patients with high prolactin are prone to excessive weight gain, and normalization of prolactin levels using dopamine activators is associated with weight loss (R).

Interestingly, gene studies have revealed that a common variant adjacent to the prolactin gene is associated with obesity (R).

4-5) Prolactin Can Cause Anxiety and Depression

A byproduct of prolactin (vasoinhibins) causes depression and anxiety.

There is a correlation between prolactin and anxiety in men (R).

Prolactin levels in unipolar depressive patients are related to dissociative symptoms (R).

Prolactin may cause mood issues because of it regulates receptor potential thresholds, neuronal excitability and/or neurotransmission efficiency (R).

6) Prolactin May Worsen Migraines and Cause Pain

High prolactin may contribute to the pain in migraines, which can subside when given a drug to decrease prolactin (R).

Women given a drug to lower prolactin experienced improvement in their migraines (R).

7) Prolactin Inhibits Blood Vessel Growth

Prolactin increases vasoinhibins, which are known for their inhibiting effects on blood vessel growth, vasopermeability, and vasodilation (R).

Disturbances of the prolactin/vasoinhibin axis are associated with the development of retinal diseases, cardiac diseases, and diseases occurring during pregnancy (R).

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8) Prolactin May Cause Cystic Fibrosis

Prolactin is one of the possible causes in cystic fibrosis (R).

9) Prolactin May Increase Cancer Risk

Prolactin may increase breast and prostate tumors (R).

Prolactin: The Good

1) Prolactin and Electrolyte Balance

Prolactin is responsible for fluid, sodium, chloride, and calcium transport across intestinal epithelial membranes (R).

Prolactin acts on the kidney to promote sodium, potassium, and water retention (R).

2) Prolactin Is an Important Hormone During Sex

Prolactin provides the body with sexual gratification after sexual acts.  The hormone counteracts the effect of dopamine, which is responsible for sexual arousal. This is thought to cause the sexual refractory period (R).

The amount of prolactin can be an indicator of the amount of sexual satisfaction and relaxation. Unusually high amounts are suspected to be responsible for impotence and loss of libido (R).

Prolactin levels have also been found to rise with use of the drug MDMA (Ecstasy) (R).

3) Prolactin Increases Neurogenesis

In rats, prolactin can induce neurogenesis in the subventricular zone and the dentate gyrus (R).

Technical

The body produces 3 different forms of prolactin: little (14kDa), big (16kDa), and big-big (23kDa) prolactin (R).

Prolactin is secreted in a pulse-like fashion with a pulse frequency ranging from about 9-14 pulses per 24 hours.

  • Prolactin is found to be secreted from the uterus, placenta, immune cells, brain, breasts, prostate, skin, and fat tissue (R).
  • Prolactin receptors are present in the breasts, ovaries, pituitary glands, heart, lung, thymus, spleen, liver, pancreas, kidney, adrenal gland, uterus, skeletal muscle, skin and areas of the brain (R).
  • The 14 kDa form is most responsive to stimulation or suppression outside the pituitary gland (R).
  • The 16 kDa form has inhibitory effects on blood vessel and tumor growth (R).
  • The 23 kDa form creates new blood cells (R).
  • In humans, prolactin increased spermine and spermidine synthesis which are required for milk production (R).
  • Prolactin activates the Jak2/STAT5 pathway, which is responsible for milk production (R).

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

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18 COMMENTS

  • AnneT

    Hi there,
    I have Pituitary Disorders, which in due to insufficient in estrogen and progesterone. I got pregnant thru IUI. At the hospital, I was able to fed my babies but I started formula the third day since babies weight drop, I have been pumping for 3 months now and nothing is coming out. I check my prolactin number and it is low. If I continue pumping do you think my milk supply will come in, since I do have low in those hormones. My babies are stop latching since there is no milk….

  • Fiona

    This is so interesting. I have really bad pain in all my joints when breastfeeding. Doctor had no idea what it could be. Looking up ‘joint pain while breastfeeding’ brings up forum after forum of breastfeeding mothers talking about this pain, many saying doctors had no idea about it, and no info anywhere on what might cause it. Most of them say that it starts a few days after giving birth (around day 4-5 for me, right when the estrogen and progesterone drop off) and is worst overnight and first thing in the morning (I’ve just learned that prolactin is highest overnight and just before you wake up). It doesn’t offer any solutions, and maybe there are none – probably trying to reduce your prolactin levels when lactating isn’t a good idea – but I feel so much better knowing a probable cause.

  • Ben Waldner

    4- 5 Anxiety and depressen – does this point only counts for men?

  • K

    I have read that vitamin b6(p5p) reduces prolactin. Ithis might be the easiest option. I reduced mine with myomin and/or Maca. I moved on to a much cheaper option DIM instead of myomin and I think the levels are still under control(because there are no headaches.) There’s some link between estrogen dominance and prolactin. As always research before you take any of these since I’m not a doctor.

  • Mina

    Hi, i just wanna ask how can i make normal prolactin my doctor told me its high levels its 60.0 and maybe be that’s why iam not getting pregnancy?

    1. Some_Blonde_Bimbo

      Your safest bet is an adaptogenic herb named Vitex. It will reduce prolactin (and increase dopamine) increases LH and FSH which will encourage ovulation which then increases progesterone. Progesterone is important so you can hold the baby to term.

      Cabergoline and other prescribed medications that increase dopamine (which suppress prolactin) are too dangerous around the time of conception.

      It may take up to 4-5 months to work completely and expect some real weird emotional purging the first 2 weeks of taking it. It will also rev up your libido and balance out an imbalanced hormonal system.

      I used the Swisse brand.

  • David

    This article is a gold mine

    I took 1 mg cabgergoline once a week for 6 months when I was 21. I’ve never been the same since.

    Within the first month of taking it I broke up with my girlfriend of 2 and a half years. Moved out of my apartment of 3 years to move to Hollywood. Started going out drinking, going to strip clubs. I started having issues sleeping through the whole night. I would wake up several times. Usually to check on dating apps. I started masterbating everyday, shopping compulsively, eating compulsively. Working out and exercising became impossible. I didn’t have the attention span to finish 10 reps of exercise. I went through my whole saving in two months and racked up 10,000 in credit card debt.

    It’s been almost four years now and I’ve never been the same. Have been on and off different anti depressants trying to get back to normal.

    Prolactin April 2013 – 12.7 (Range ng/ml 4.0-15.2)

    Prolactin 1/18/2016 – 4.0 – (Range 2.0-18.00 ng/ml)

    What did I do exactly? And is there anyway to get my levels back to normal?

    1. Nattha Wannissorn, PhD

      It might have something to do with your dopamine levels rather than prolactin.

      1. David

        So as I understand it my dopamine is now very high which is lowering my prolactin and my serotonin levels?

        What do I do to reverse this? Is there anything I can take?

      2. David

        Little bit confused. When dopamine goes up it lowers prolactin but increasing prolactin also increases dopamine?

        1. Nattha Wannissorn, PhD

          If you have high dopamine, it can increase prolactin.

        2. Eli

          High dopamine tells the body to stop releasing and creating more prolactin, because prolactin also raises dopamine.. its a negative feedback loop. I’m in the same boat as you, I don’t know how you work around that and reduce the dopamine, and raise the prolactin at the same time.

          1. David

            Thanks for clearing that up.

            Only thing I can think of is raising serotonin levels. Which would bring down dopamine and maybe the body makes more prolactin?

            What’s you’re situation? Why do you need to increase prolactin?

            I just don’t understand why things didn’t go back to normal for me after stopping the cabergoline.

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  • sara beyla

    My test for prolactin was taken 1 day before the periods that is 42.28 and i am 23 yrs old girl . Since 2 months i am seeing irregular periods i.e after 40 days im seeing periods ..this prolactin level could decress naturally?

    1. Nattha Wannissorn, PhD

      Gotta get diagnosed by your doctor. There’s a few causes for high prolactin, pituitary tumors, high dopamine, stress etc. Once you get the diagnosis, you can find out why your period is irregular.

  • Joann

    Is 4.4 normal for prolactin level in a non pregnant female?

  • Daz

    Prolactin levels looks to be seasonal as well ?
    eg. http://www.ncbi.nlm.nih.gov/pubmed/1585003

    I’ve seen it referred to as the ‘molting hormone’ in some circles (hair loss forums).

    1. Glad

      Its still a confusion.what are the best food to stablaize the level of prolactin

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