Introduction

Prolactin is a hormone, primarily responsible for triggering milk secretion after childbirth and also supporting breast tissue development.¹ The hormone also plays a role in regulating the immune system, metabolism and stress/anxiety responses within the human body.² Under normal conditions, prolactin levels are controlled by the brain, which in turn triggers their increase during pregnancy and returns to normal after breastfeeding has ended. 

Chiari-Frommel Syndrome (CFS) is an endocrine disorder that is caused by high levels of the prolactin hormone post-partum, which do not return to normal levels, even after breastfeeding.

What is prolactin?

Prolactin is a hormone secreted from the pituitary gland, an organ located in the brain. The primary role of this hormone is to aid the breasts in breastfeeding after birth; i.e. prolactin levels naturally increase to accommodate this change.¹ At post-partum, high levels of prolactin secretion are maintained through breastfeeding, and so is the milk supply. However, once breastfeeding is done, prolactin levels fall.

Beyond breastfeeding, prolactin also influences the regulation of the menstrual cycle (also known as periods). It specifically affects the ovulation stage of the cycle, which involves the release of an egg in a female assigned at birth. This released egg gets fertilised by sperm. Upon fertilisation, this marks the beginning of pregnancy. In elevated levels, prolactin can prohibit ovulation by interfering with the two hormones (Follicle-stimulating hormone or ‘FSH’ and Luteinising hormone or ‘LH’) that are both key to stimulating ovulation.³

How are prolactin levels regulated in the body?

In the body, prolactin is tightly regulated by two regions of the brain: the hypothalamus and the pituitary gland. Essentially, these two parts communicate with hormones to regulate prolactin levels in the body.⁴ Unlike most hormones, prolactin is prevented from being secreted; this is done by an inhibitory signal/hormone called dopamine, secreted from the hypothalamus to the pituitary gland.⁵ Dopamine is secreted at high levels to maintain the inhibition of prolactin.

On the contrary, there are certain circumstances in which the body requires higher levels of prolactin, for instance, during pregnancy, the hypothalamus secretes another hormone called thyrotropin-releasing hormone (TRH), which triggers the release of prolactin and maintains its high levels.⁶

Another key regulation of prolactin involves a ‘feedback loop’ (a necessary trigger to increase the hormone production). For prolactin, the trigger is the suckling of a baby on the nipples (located on the breast) that sends signals to the hypothalamus.⁷ These signals then tell the hypothalamus to stop the secretion of dopamine, which in turn prevents the inhibition of prolactin, allowing the prolactin levels to rise.

Dysregulation of prolactin in Chiari-Frommel syndrome (CFS)

Chiari-Frommel syndrome (CFS) is a rare endocrine disorder identified in the 19th century that results in abnormally high prolactin levels in women post-partum, who have ended the breastfeeding stage of their infant. The syndrome arises because of the failure of dopamine’s ability to prevent the secretion of prolactin, leading to elevated levels of the hormone (hyperprolactinaemia), creating a hormonal imbalance.⁸

Why dopamine fails to inhibit prolactin secretion is still misunderstood; however, some research points to it being associated with abnormalities in the pituitary gland, but it is still a novel area. It is important to distinguish this condition from other, more common causes of hyperprolactinaemia. Elevated prolactin can also result from pituitary tumours (prolactinomas), certain medications, thyroid disorders, or even stress^.9 In Chiari-Frommel Syndrome, however, no tumour is found, and the link to the postpartum period is a defining feature.

Symptoms and clinical features 

The main symptoms that could indicate CFS include:

• Continued lactation even after breastfeeding has ended (galactorrhoea)
• Absence of periods (amenorrhoea) or infrequent/irregular periods (oligomenorrhoea)
• Reduced sex drive 
• Mood changes 

These symptoms will present after pregnancy and the breastfeeding stage has ended, typically persisting for over six months, and a woman may experience them simultaneously.

Diagnosis

Diagnosing CFS involves a careful clinical assessment to distinguish it from other common conditions that cause high prolactin levels. Doctors begin by taking a detailed medical history, focusing on recent childbirth, breastfeeding patterns, and any changes to the menstrual cycle. The presence of symptoms such as persistent milk secretion, absent or irregular periods, and infertility can be the initial indicators that point towards the condition.

Blood tests are the next step to diagnosing CFS. These include measuring prolactin levels to confirm whether they are abnormally high. Thyroid hormone levels and carrying out a pregnancy test, since thyroid disease and pregnancy can both affect prolactin levels. If blood test results confirm high prolactin, doctors may arrange imaging tests, most often a pituitary MRI, to look for structural causes like a prolactin-secreting tumour (prolactinoma).¹⁰

For Chiari-Frommel Syndrome, the diagnostic criteria typically include persistently increased prolactin levels, absence of a pituitary tumour, and a clear link to the postpartum period. Because many other conditions and even certain medications can cause hyperprolactinaemia, it is vital to rule out other causes before confirming the diagnosis. This careful process helps ensure that treatment is appropriate and tailored to the individual.

Management and treatment

The management of Chiari-Frommel Syndrome aims to correct high prolactin levels and restore normal reproductive function. The most common treatment is with medicines called dopamine agonists. These drugs imitate dopamine action while being prolactin inhibitors and correcting prolactin levels.¹¹

Dopamine agonists are usually very effective, although some women may experience side effects such as nausea, dizziness or headaches. Starting with a small dose and increasing it gradually often makes the treatment easier to tolerate. Moreover, blood tests are carried out regularly to make sure prolactin levels are responding to the medicine and are lowering. In rare cases, Chiari-Frommel Syndrome may resolve on its own, but medication is usually helpful in speeding up recovery and reducing symptoms.

Treatment is decided based on the woman’s condition. Fertility support may be offered if ovulation does not resume naturally, while hormonal therapies may also be offered to help regulate the menstrual cycle in those not seeking pregnancy. Psychological support and counselling are also important, as the condition can affect self-esteem, relationships and overall wellbeing.

Living with Chiari-Frommel syndrome

Although rare, CFS can have a significant impact on daily life. Ongoing milk production after breastfeeding has stopped can be distressing, while fertility problems may cause emotional strain. Many women also notice changes in mood or a reduced sex drive, which can affect relationships. Having access to supportive healthcare teams and talking openly with family and friends can make these challenges easier to manage.

With treatment, the outlook is usually positive, with most women regaining normal menstrual cycles, and many can conceive naturally once prolactin levels are corrected. For those who continue to face difficulties, fertility treatments can provide further options. Long-term follow-ups with an endocrinologist also help to keep hormone levels stable and ensure symptoms do not return.

Additionally, lifestyle steps such as maintaining a healthy diet, reducing stress and getting enough rest can also support recovery. Some women find it helpful to join patient support groups or access counselling, which can reduce feelings of isolation and provide reassurance that they are not alone in managing the condition.

Summary 

Prolactin is a hormone that plays an important role in pregnancy, breastfeeding, fertility and overall health. The brain regulates it via signals, but in Chiari-Frommel Syndrome, this regulation is disrupted, leaving prolactin levels high long after breastfeeding has ended. The main symptoms include persistent milk production, absent or irregular periods and fertility difficulties. Anyone experiencing these signs after pregnancy should seek medical advice, as effective treatments are available. Medicines that reduce prolactin are usually successful, and with proper care, most women recover well and can regain fertility.