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Explaining Unexplained Infertility: Have You Checked Your Prolactin Level?

Updated: May 21, 2020

What is Prolactin?

Prolactin is a hormone that is mainly secreted by your pituitary gland; it is often referred to as the breast-feeding hormone because it is naturally high in nursing women where it has the effect of naturally supressing ovulation. A high level of prolactin is known as hyperprolactinaemia.

What Causes a Raised Prolactin Level?

Prolactin is naturally raised when we are breastfeeding as it is the hormone that supports milk production in the breasts. It acts as a natural contraception through this time, reducing the body's ability to ovulate. While it is possible to conceive while breastfeeding, the majority of women would find it difficult.

It is rare, but possible for hyperprolactinaemia to be caused by a tiny tumour on the pituitary gland – these tumours are rare (approximately 4 people out of every 10,000), usually benign, and their prolactin-generating effect can easily be controlled with medication. If your prolactin level is very high, your doctor should refer you for an MRI to check whether you have any sign of a nodule or small tumour on your pituitary gland.

For some women, prolactin may be raised even if a woman is not breast-feeding and has no pituitary tumour. Several lifestyle factors can contribute to a high prolactin level, factors such as a persistent lack of sleep, ongoing high stress levels, depression and diet. Prolactin has an inverse relationship with dopamine, so if your dopamine levels are low, your prolactin may increase. Low thyroid function is also associated with high prolactin, but it is possible that the problem is at the level of the pituitary gland so it is worth addressing prolactin before looking to medicate the thyroid.

Regular running without a supportive bra can cause sufficient 'jiggling' to cause a higher prolactin level, as can excessive 'nipple action' (if you are having a blood test to check prolactin, avoid going for a run or stimulating your nipples for a day or two before your test).

Some medication can also encourage a higher prolactin level - certain antidepressants have been shown to increase prolactin and some medication for stomach acid issues can also raise the prolactin level.

How Does a Higher Prolactin Level Affect Fertility?

Prolactin is mainly synthesised in the pituitary gland, which is also responsible for the production of Follicle Stimulating Hormone (FSH); if the pituitary gland is pumping out too much prolactin, this can suppress the production of FSH. FSH is the hormone that signals to your ovary to grow follicles and it plays a key role in the processes leading up to ovulation. In this way, a high prolactin level can have a negative impact on the quality of the developing follicle and egg, and in some cases it can prevent the follicle from maturing to the point where it is able to release an egg.

Some Signs It May Be Good To Check Your Prolactin Level

  • Lack of Cervical Mucus Hyperprolactinaemia can suppress FSH which will have a knock on effect on the production of oestrogen in the ovary. This in turn will reduce the amount of cervical mucus that is produced; cervical mucus is an essential aspect of your fertility as it enables sperm to move safely through to the egg, protecting and nourishing it as it goes. If you have persistently low levels of oestrogen, or a distinct lack of cervical mucus, it may be time to check your prolactin level.

  • Hair Loss If you notice symptoms of excess hair loss, it may be worth getting your prolactin level checked because high prolactin levels have been linked to high DHEA levels which can in turn lead to an increase in testosterone symptoms.

  • Symptoms of Poor Testosterone Management (acne, hair loss, irregular cycles) If you do not ovulate, or have irregular or long cycles (>35 days) it is worth checking prolactin levels – symptoms of high prolactin can mimic some of the testosterone management issues that are frequently associated with polycystic ovarian syndrome (PCOS) as it can cause an increase in DHEA and subsequently an increase in testosterone.

  • Short Luteal Phase If your luteal phase is short, or if your progesterone level is a bit low, that may also indicate it is time to check your prolactin level because a raised prolactin level can also shorten and weaken the luteal phase of your cycle.

  • Producing Breast Milk Prolactin is known as the breast-feeding hormone because of the role it plays in stimulating the breasts to produce milk. If you have noticed milky secretions from your breasts, you should definitely check your prolactin level.

Other Issues to Check

Hyperprolactinaemia is sometimes associated with other issues such as liver or kidney issues, PCOS or hypothyroidism. If you do find you have high levels of prolactin, you will need to investigate further to determine whether PCOS or hypothyroidism is also involved as both can have a negative impact on your fertility if left undetected. Approximately 1 in 6 people with PCOS also have hyperprolactinaemia.

Checking Your Prolactin Level

Prolactin can be checked easily with a simple blood test. If your GP or fertility clinic runs some blood tests and you have any of the above symptoms, request that they also check your prolactin level. You may have some resistance from your GP because the NICE guidelines recommend prolactin only be checked in women with a known ovulatory disorder, unusual production of breast milk or a pituitary tumour. If your doctor is reluctant to test your prolactin level, you can use a service such as Medichecks who offer a simple finger-prick test to check prolactin:

** If possible, it is best to check your prolactin in the first half of your cycle, in the morning, and avoid excessive nipple stimulation before your test!

When is a High Prolactin Level OK?

If your prolactin level is high, but you have no symptoms of hyperprolactinaemia it is possible that you have high levels of something called macroprolactin. Macroprolactin is a larger prolactin substance that is counted alongside normal prolactin in the basic test, but macroprolactin levels are not thought to interfere with fertility or cause any of the other signs of high prolactin. Approximately 15% of results showing a high prolactin level would find this was actually caused by a high macroprolactin level if they were to look a bit deeper. There is an advanced test which determine how much of a high prolactin level is really macroprolactin, but the test is more expensive and less commonly used.

How to Treat Hyperprolactinaemia

  • Medication If you have a prolactinoma, you may be prescribed cabergoline or bromocriptine by your doctor (a prolactinoma would usually cause extremely high levels of prolactin (over 1000IU/L)).

  • Vitex From an alternative perspective, evidence suggests that Vitex (agnus castus) has a prolactin-lowering effect, equally as effective as Bromocriptine. Vitex effects hormone production by disrupting the function of the pituitary gland, it is not a herbal supplement to stay on for a long period of time. Anecdotal evidence suggests that taking Vitex for between 3-6 months can help to reset prolactin levels – take daily with a break of 5 days a month. Once ovulation normalises and your cycle is regular, adjust the timing so that you only take it during the luteal phase of the cycle. One study of a group of women with hyperprolactinaemia showed that when they took Vitex for 3 months, their average luteal phase increased from 3.4 days to 10.5 days (Arentz S. et al, 2014)

  • Stress-Management Stress is a contributing factor to hyperprolactinaemia, so put some concerted effort into working out how to manage your stress and encourage a more mindful, relaxed state of mind. Meditation, mindfulness, yoga and gentle walking are all good habits to adopt.

Avoid Beer! Reduce your alcohol intake, and avoid beer which was traditionally given to nursing women to encourage breast feeding!

To Conclude

High Prolactin levels can interfere with ovulation and negatively impact fertility. If you show any signs of high prolactin, it is definitely worth checking your prolactin level with a blood tests to make sure that it is not part of your picture. Prolactin levels can fluctuate, if you find you have a high level of prolactin, it is worth rechecking it to be sure.

Alexandra O'Connor

Fertility Acupuncture Specialist & Fertility Mentor Essex Fertility

Arentz S, Abbott JA, Smith CA, Bensoussan A. Herbal medicine for the management of polycystic ovary syndrome (PCOS) and associated oligo/amenorrhoea and hyperandrogenism; a review of the laboratory evidence for effects with corroborative clinical findings. BMC Complement Altern Med. 2014;14:511. Published 2014 Dec 18. doi:10.1186/1472-6882-14-511

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