notebook with prolactin written on it

Prolactin (PRL) Hormone: Function, Healthy Range And More

The hormone behind breast milk production, prolactin levels increase when you’re pregnant. Here’s out how prolactin affects fertility.

A hormone better known by women that are breastfeeding, the prolactin hormone can also affect women who are trying to get pregnant, as well as men. This special hormone is the one behind the growth of your breasts, as well as milk production.

Here’s a guide to help you better understand prolactin, what it does, how it can affect your chances of getting pregnant and how to test for your prolactin levels.


What is prolactin hormone?

Prolactin, also known as PRL or lactotropin, is a hormone that is responsible for functions such as lactation, milk production, certain breast tissue development and more [1]. In short, this hormone causes your breasts to grow and produce milk.

It is produced primarily in our pituitary gland, though your central nervous system, uterus, immune system and other glands are also able to produce prolactin [1]. Dopamine and oestrogen, control the production and release of prolactin from the pituitary gland [1].

What causes high prolactin levels? 

It is normal for prolactin levels to increase during pregnancy and it will remain elevated after giving birth, with the duration dependent on whether the woman continues to breastfeed [3]. If the woman chooses not to breastfeed, prolactin levels can return to normal within 2 to 3 weeks of giving birth [1].

However, there are some factors that could contribute to the slight and temporary increase in prolactin levels which are unrelated to pregnancy and breastfeeding such as [1]:

  • Exercise
  • Physical stress, which could also include experiencing pain
  • Sexual intercourse 
  • Eating a meal
  • Nipple stimulation unrelated to chestfeeding
  • Injury to your chest area

Several causes for abnormally high prolactin levels include [2, 7]:

  • Prolactinoma
  • Anorexia (an eating disorder)
  • Chest injuries or irritation
  • Polycystic ovarian syndrome (PCOS) 
  • Kidney disease
  • Liver failure
  • Pituitary disorders
  • Certain health conditions
  • Certain medications taken

What causes low prolactin levels? 

Prolactin levels tend to be lower in people assigned male at birth (AMAB), as well as women that are not pregnant or not breastfeeding [1]. Abnormally low levels of prolactin can be caused by hypopituitarism a condition where there is a lack of hormones made by your pituitary gland. This is typically caused by abnormal pressure being exerted on the pituitary gland, or due to damage to the pituitary gland [2].


Symptoms of high prolactin levels

Here are the symptoms of high levels of prolactin you can look out for, which can differ between women and men.

For women, symptoms can include [2]:

  • Irregular periods, or changes in your menstruation cycle
  • Infertility  
  • Milk discharge from your nipples when you are not pregnant or nursing
  • Breast tenderness
  • Pain or discomfort during sex as a result of vaginal dryness

For men, symptoms can include [3]: 

  • Erectile dysfunction
  • Reduced sex drive
  • Milk-like discharge from nipples (rare)
  • Breast enlargement

Unlike having high levels of prolactin, having low levels of prolactin is harder to spot. A sign of having low prolactin is the lack of production of breastmilk after giving birth [1].

If some of those symptoms sound familiar, and you’re curious about the level of hormones in your body, consider getting a hormone test done from the comforts of your home. A handy kit like the twoplus Fertility Hormone Test Kit will test for key fertility hormones, such as: 

  • Prolactin (PRL)
  • Anti-Mullerian Hormone (AMH)
  • Follicle Stimulating Hormone (FSH)
  • Thyroid Stimulating Hormone (TSH)
  • Free Thyroxine (FT4)
Try The twoplus Hormone Test Kit


How does prolactin levels affect fertility?

cropped shot of the female reproductive system

High levels of prolactin can cause infertility if left untreated [3].

For females, problems such as irregular periods, discomfort during penetrative sex can affect your chances of conceiving. High levels of prolactin can also prevent your ovaries from releasing eggs [4].

For males, conception can be adversely affected by the lower sex drive and erectile dysfunction potentially caused by high levels of prolactin [3]. Prolactin can also affect the testes from producing testosterone, and in rare cases, cause infertility [3].

Low levels of prolactin on the other hand, can lead to mothers producing insufficient breast milk after giving birth [5].


What is considered a normal level of prolactin?

Is there really a ‘normal’ level to follow for prolactin levels in your body?

While studies differ in terms of the levels of prolactin for men and women, here is a general gauge for you to reference [1]:

  • For women who are not pregnant: Less than 25 nanograms per millilitre (ng/ml)
  • For men: Less than 20 ng/ml
  • For women who are pregnant or breastfeeding: Levels are much higher, up to 400 ng/ml

But wait, how are you supposed to test for your prolactin levels by ng/ml? This is where a blood test comes in.


How can I test for prolactin?

You can get a prolactin test done, to measure the amount of prolactin you have in your blood. This is typically done via a blood test conducted by a healthcare professional [1].

As prolactin levels tend to be highest in the morning, you will need to take the prolactin test about 3 hours after waking up. You could also be advised to avoid stress, exercising and stimulating your nipples in the hours leading up to the test as this could affect the results [3].

When should you get a prolactin test done? Your doctor could ask you to get a prolactin test done if you display symptoms that could be related to your prolactin levels.


Treatment for high levels of prolactin

The treatment of high prolactin levels depends on the diagnosis and cause. Not all cases need to be treated. Bromocriptine and cabergoline are the most commonly used medicine [2, 3].

If your prolactin levels are extremely high, it could be a sign of prolactinoma — a benign tumour of the pituitary gland causing you to produce excess prolactin [1].

If you are diagnosed with prolactinoma, medication can be prescribed to reduce the size of the tumour and lower the prolactin levels, though some cases could require surgery or radiation therapy [6].


In summary

High levels of prolactin are far more common than low levels of prolactin [3]. As we have discussed above, both can have an impact on your body but high levels of prolactin come with more symptoms and potentially greater concerns particularly around fertility.

Take a quick hormone test to check on your prolactin levels, and at the same time, also test for other critical hormones that affect your fertility, such as AMH and FSH.

The twoplus Fertility Hormone Test Kit gives you a clear view of your reproductive health, testing for prolactin as well as highlighting other potential fertility problems such as endometriosis, and PCOS. All this, done via a quick blood collection from wherever you prefer, be it at home, the office or anywhere else.


Are you taking too long to conceive? Check out our Getting Pregnant 101 Guide for must-know TTC tips below & above 35 years old.


Learn More About This At-Home Hormone Test 
[1] Cleveland Clinic, Prolactin, 
[2] WebMD, What Is A Prolactin Test?, 
[3] MedicalNewsToday, Prolactin Levels: Why To Get A Prolactin Test And What To Expect,
[4] Verywell Family, Your Guide to Prolactin and Breastfeeding, 
[5] You And Your Hormones, Prolactin,  
[6] Mayo Clinic, Prolactinoma, 
[7] MedicalNewsToday, What Are High Prolactin Levels And Prolactinomas, And What Are The Side Effects?,