Hyperprolactinemia: Symptoms, Causes & Fertility Impact

Why High Prolactin Matters When You Are Trying to Conceive

If your periods have become irregular or stopped, or you have noticed a milky discharge from your nipples when you are not pregnant or breastfeeding, one hormone worth checking is prolactin. When prolactin stays high outside pregnancy and breastfeeding, the condition is called hyperprolactinemia. It is one of the more treatable hormonal causes of infertility, and many of the women I see with it go on to conceive once their levels are brought under control.

This article is for education only. It does not replace an examination, diagnosis or treatment plan from a qualified doctor.

What Is Prolactin and What Does It Do?

Prolactin is made by the pituitary gland at the base of the brain. Its best-known job is to trigger milk production after delivery. Small amounts are present in every woman and man at all times.

Prolactin is normally held in check by dopamine, a chemical released from the hypothalamus. Anything that lowers dopamine or stimulates the prolactin-producing cells lets prolactin rise. Most laboratories treat a non-pregnant woman's value below roughly 25 ng/mL as normal, though reference ranges differ between labs, so always read your result against your own report's range.

Prolactin also talks to the reproductive system. When it is high, the brain sends weaker and less regular signals to the ovaries, which is exactly what stops ovulation.

Symptoms of Hyperprolactinemia

Some women have no symptoms at all and the high level is found during a fertility work-up. Others notice:

• Irregular, infrequent or absent periods. Periods more than 35 days apart, or none for three months or longer.
• Galactorrhea. A milky discharge from both nipples when you are not pregnant or breastfeeding.
• Difficulty conceiving, because ovulation is not happening regularly.
• Low sex drive, vaginal dryness or painful intercourse, caused by low oestrogen.
• Headaches or changes in vision, especially loss of side vision. These can occur when a larger pituitary tumour presses on nearby structures.

Irregular cycles have many causes, so it helps to read about irregular periods, their causes and treatment and how to tell whether you are actually ovulating.

What Causes High Prolactin?

The cause decides the treatment, so finding it matters.

Pituitary tumours (prolactinoma)

A prolactinoma is a benign (non-cancerous) growth of prolactin-producing cells in the pituitary. Those under 10 mm are called microprolactinomas and are common, especially in younger women; they rarely grow. Those of 10 mm or more are macroprolactinomas and need closer monitoring because they can press on the optic nerves.

Thyroid disease

An underactive thyroid (hypothyroidism) raises TRH, a brain hormone that also stimulates prolactin. Treating the thyroid often normalises prolactin. This is why thyroid and prolactin are tested together. See how the thyroid affects fertility.

Medicines

Drugs that block dopamine can raise prolactin. These include some antipsychotics, some antidepressants, certain blood-pressure medicines and anti-nausea drugs such as metoclopramide. Never stop a prescribed medicine on your own; talk to the doctor who prescribed it.

Other causes

Physical or emotional stress, intense exercise, chest-wall irritation (from surgery, shingles or tight clothing), chronic kidney disease and severe liver disease can all raise prolactin. Some women also have macroprolactinemia, where prolactin clumps into large, biologically inactive molecules. Standard tests read this as "high" even though it is harmless, which is why a repeat or special test is sometimes needed.

How High Prolactin Affects Fertility

Prolactin at high levels suppresses the pulsing release of GnRH from the hypothalamus. Without those pulses the pituitary releases less FSH and LH. The result:

1. Follicles do not mature properly.
2. The mid-cycle LH surge that triggers ovulation is weak or missing, so ovulation does not happen.
3. Even when ovulation does occur, the second half of the cycle may be weak, with too little progesterone to support implantation. This overlaps with what is described as a luteal phase defect.

Other hormonal problems can look similar, including PCOS and thyroid disease. Read more on hormonal imbalance and infertility in women.

How Hyperprolactinemia Is Diagnosed

Blood tests

• Serum prolactin. Ideally taken in the morning, two to three hours after waking, after 15 to 20 minutes of quiet rest, because stress and even a heavy meal can raise it temporarily. A mildly raised first result is usually repeated.
• TSH to check for an underactive thyroid.
• Pregnancy test, kidney and liver tests where relevant.
• Macroprolactin screening if the level is high but there are no symptoms.

MRI of the pituitary

If prolactin is persistently high and medicines and thyroid disease have been ruled out, an MRI of the pituitary gland shows whether there is a microprolactinoma or macroprolactinoma, how large it is and whether it presses on the optic nerves. It also gives a baseline to compare with later.

Treatment for High Prolactin

Most hyperprolactinemia is treated with tablets, not surgery.

Dopamine agonists

These medicines act like dopamine on the pituitary, lowering prolactin and shrinking prolactinomas.

Your doctor will choose between them depending on your situation and whether you plan to conceive soon. Doses are increased gradually and prolactin is rechecked every few weeks to months.

Treating the underlying cause

If the cause is hypothyroidism, thyroid treatment comes first. If a medicine is responsible, your prescriber may be able to switch it to one that does not raise prolactin. Surgery or radiotherapy is reserved for the few tumours that do not respond to tablets or that threaten vision.

Getting Pregnant With Hyperprolactinemia

The outlook is encouraging. Once prolactin falls to normal, the brain-ovary signals recover, ovulation resumes and many women conceive naturally.

• After conception. In women with small tumours, the dopamine agonist is usually stopped once pregnancy is confirmed. Women with macroprolactinomas need closer follow-up with an endocrinologist, because the hormones of pregnancy can make the tumour grow. Do not stop or restart medicines without medical advice.
• If ovulation does not return. If cycles stay irregular after prolactin is normal, ovulation induction medicines such as letrozole may be added, often with follicle tracking. Learn more about ovulation induction.
• If other factors are present. Blocked tubes, low sperm counts or advanced maternal age may mean IUI or IVF is needed. Once prolactin is controlled, outcomes depend mainly on the woman's age, ovarian reserve and other findings, not on the past high prolactin itself. See how age affects fertility.

When Should You See a Fertility Specialist?

See a doctor if your periods are irregular or absent, you have nipple discharge outside pregnancy or breastfeeding, you have persistent headaches with vision changes, or you have been trying to conceive for a year without success (six months if you are over 35).

Each woman's cause, and therefore her plan, is different. In my practice in Chennai I review your hormones, thyroid and imaging together, correct what is reversible and time treatment around your plans to conceive. If you would like an evaluation, book a consultation with Dr. Rukkayal Fathima.

Medical disclaimer: the information above is general and educational. Diagnosis and treatment depend on your individual tests and history. Please consult a qualified doctor before starting, stopping or changing any medicine.