How to Explain Prolactin to a Patient
Prolactin is a hormone made by your pituitary gland (a small gland at the base of your brain) that normally helps women produce breast milk after having a baby, but when levels are too high when you're not pregnant or breastfeeding, it can stop your periods, cause breast milk leakage, and make it difficult to get pregnant. 1
What Prolactin Does in Your Body
Prolactin's main job is to trigger breast milk production after childbirth, which is why levels naturally rise during pregnancy and breastfeeding. 1
When prolactin levels are too high outside of pregnancy, it interferes with the hormones that control your menstrual cycle and fertility by blocking a hormone called kisspeptin in your brain, which then stops the release of the hormones (LH and FSH) needed for ovulation. 1
What Happens When Prolactin Is Too High
In Women
Your periods may become irregular, infrequent, or stop completely (amenorrhea), which is one of the most common signs of high prolactin—this occurs in about 55% of women with amenorrhea and 37% of women with irregular cycles. 1, 2
You may notice breast milk leaking from your nipples (galactorrhea) even though you're not pregnant or nursing, though this doesn't happen to everyone with high prolactin. 1, 2
You may have difficulty getting pregnant because high prolactin prevents normal ovulation, making this a common cause of infertility in women with these symptoms. 1, 3
In Men
- Men with high prolactin may experience decreased sex drive, difficulty with erections, and breast enlargement (gynecomastia) due to the same mechanism of suppressed reproductive hormones. 1
Common Causes of High Prolactin
The most common pathological cause is a benign (non-cancerous) tumor in the pituitary gland called a prolactinoma, which continuously produces too much prolactin—the size of the tumor usually correlates with how high your prolactin level is. 1
Many medications can raise prolactin levels, particularly those that affect dopamine (the brain chemical that normally keeps prolactin in check), including some medications for nausea, psychiatric conditions, and high blood pressure. 1
An underactive thyroid gland (hypothyroidism) causes high prolactin in about 43% of women and 40% of men with this condition, which is why thyroid testing is always done when prolactin is elevated. 1
Kidney or liver disease can also elevate prolactin levels—chronic kidney disease causes high prolactin in 30-65% of adult patients. 1
Why This Matters for Your Health
High prolactin is treatable, and treating it can restore your menstrual cycles and fertility—studies show that 76-82% of women with infertility and high prolactin can achieve pregnancy with appropriate treatment. 3
If a pituitary tumor is causing the high prolactin, it can be effectively treated with medication (dopamine agonists like cabergoline) in the vast majority of cases, which both lowers prolactin and shrinks the tumor without needing surgery. 1, 4
Large tumors can occasionally cause headaches or vision problems if they press on nearby structures, but these symptoms typically improve with treatment—visual field defects resolve in about 67% of patients treated with dopamine agonists. 1
What to Expect with Testing
A simple blood test measures your prolactin level, and timing doesn't matter—it can be drawn at any time of day, and results are usually available within a day. 1, 5
If your prolactin is mildly elevated, your doctor may repeat the test because stress alone can temporarily raise levels up to five times normal. 1, 5
Your doctor will check your thyroid function and review all your medications to rule out these common reversible causes before proceeding with further testing. 1, 5
If prolactin remains significantly elevated after excluding medication and thyroid causes, an MRI of your pituitary gland will be ordered to look for a prolactinoma or other structural cause. 5, 4
Important Points About Treatment
Most cases of high prolactin are very treatable with medication, and many women see their periods return and successfully conceive once prolactin is normalized. 3
Even without treatment, high prolactin often follows a benign course—in one study of 25 women followed for an average of 11 years, 7 of 22 women with absent periods had them return spontaneously, and only 1 patient showed slight tumor progression. 6
The goal of treatment is to normalize your prolactin level, restore your menstrual function and fertility if desired, and prevent any complications from tumor growth. 1, 4