Overview
A prolactin test measures the amount of prolactin hormone in your blood. This hormone plays a role in reproductive health, menstrual cycles and fertility. When your prolactin levels are too high or too low, you may notice irregular periods, breast discharge or difficulty conceiving. This article explains why prolactin testing is done, what the results mean and when you may need treatment. Prolactin is a hormone made by your pituitary gland that plays a vital role in reproductive health, menstrual cycles and milk production after childbirth. Measuring prolactin levels through a simple blood test can help uncover the reasons behind irregular periods, unexplained breast discharge or difficulties with fertility. Understanding your prolactin levels gives insight into your hormonal balance and overall reproductive health. In this guide, we’ll explore what a prolactin test is, why it’s done, what the results mean and the normal range you should know.
What Is Prolactin Test?
A prolactin test is a test that measures how much prolactin hormone your pituitary gland is producing.
Prolactin helps regulate menstrual cycles, ovulation and milk production. When prolactin levels become too high or too low, it can affect fertility, libido, breast changes and hormonal balance. Prolactin testing is commonly included in fertility evaluations and assessments of menstrual irregularities.
Why Is a Prolactin Test Done?
Doctors recommend a prolactin blood test when you show signs of hormone imbalance or unexplained fertility concerns.
Common reasons include:
- Irregular or absent periods
- Breast discharge not related to pregnancy or breastfeeding
- Difficulty conceiving
- Low libido
- Erectile issues (in men)
- Symptoms of pituitary imbalance
A prolactin test helps your doctor understand whether your pituitary gland is producing too much or too little of the hormone.
What Is the Normal Range for a Prolactin Test?
If you’re wondering what is prolactin test normal range, it’s important to know that expected prolactin levels can vary based on your sex, overall health and the laboratory performing the test. Prolactin levels also differ during pregnancy and breastfeeding.
Typical prolactin test normal ranges are:
| Group | Normal Prolactin Level* |
|---|---|
| Women (non-pregnant) | < 25 ng/mL |
| Men | < 15-20 ng/mL |
| Pregnant Women | 80-400 ng/mL |
*Ranges may vary by laboratory.
What Causes High Prolactin Levels?
High prolactin (hyperprolactinaemia) can happen due to stress, hormonal imbalance or medical conditions like chronic kidney or liver conditions. Some of the possible causes include:
- Pituitary Disorders Small benign tumours (prolactinomas) can increase prolactin production.
- Medications Certain medicines, including antidepressants, antipsychotics and blood pressure drugs, may raise prolactin levels.
- Hypothyroidism Low thyroid hormones can stimulate the pituitary gland to release more prolactin.
- Stress and Poor Sleep Physical or emotional stress can temporarily increase prolactin levels.
- Chest Wall Stimulation Injury, irritation or even excessive physical stimulation can raise levels.
- Pregnancy and Breastfeeding Naturally increase prolactin levels.
What Causes Low Prolactin Levels?
Low prolactin is less common but can occur when your pituitary gland is not producing enough hormone.
Potential causes include:
- Pituitary dysfunction
- Certain medications
- Autoimmune conditions
- Low oestrogen levels
- Genetic conditions (rare)
How Do Doctors Perform a Prolactin Test?
A prolactin test is a simple blood draw done in the morning, three to four hours after you wake up, because that is when the levels are most stable. A health care professional will draw a small sample of blood from your vein in your arm using a fine needle. Once the needle is inserted, your blood is collected into a vial or test tube. You may feel a brief sting when the needle goes in or out, but the discomfort usually passes quickly. The entire process is simple and typically takes only a few minutes.
Your doctor may:
- Ask you to rest before the test (stress raises prolactin)
- Check your thyroid levels alongside prolactin
- Repeat the test if the results are unexpectedly high
How Should You Prepare for a Prolactin Test?
Small lifestyle steps can help you get accurate results. You might be advised to:
- Take the test early in the morning
- Avoid sexual activity the night before
- Minimise stress
- Avoid nipple stimulation
- Get enough sleep
- Inform if taking any medications
What Do Your Prolactin Test Results Mean?
Your doctor will make out your results based on your symptoms, hormone levels and medical history.
If prolactin levels are high, you may experience:
- Irregular periods
- Breast discharge
- Reduced ovulation
- Low libido
If prolactin levels are low, you may experience:
- Difficulty in breastfeeding
- Menstrual irregularities
- Low oestrogen symptoms
When Should You Contact Your Doctor?
Speak with your doctor if you notice these symptoms:
- Unexpected breast discharge
- Changes in periods
- Difficulty conceiving
- Persistent headache or vision changes (rare, but important to check)
The Bottom Line
Prolactin plays an important role in your reproductive and hormonal health. When your prolactin levels become too high or too low, you may notice changes in your menstrual cycle, fertility or breast tissue. A prolactin test helps you and your doctor understand whether hormonal balance is contributing to your symptoms. With the right assessment, most prolactin-related concerns can be managed effectively.
Table of Contents
- What Is Prolactin Test?
- Why Is a Prolactin Test Done?
- What Is the Normal Range for a Prolactin Test?
- What Causes High Prolactin Levels?
- What Causes Low Prolactin Levels?
- How Do Doctors Perform a Prolactin Test?
- How Should You Prepare for a Prolactin Test?
- What Do Your Prolactin Test Results Mean?
- When Should You Contact Your Doctor?
- The Bottom Line
Common Questions Asked
Can medications affect prolactin levels?
Yes. Certain medications, including antidepressants, antipsychotics and blood pressure drugs, can temporarily raise prolactin levels. Your doctor may review your prescriptions before interpreting test results.
Can men have prolactin-related problems?
Although less common, high prolactin in men can cause erectile dysfunction, reduced libido, infertility and sometimes breast enlargement (gynecomastia).
How often should prolactin be tested?
Frequency depends on your symptoms and treatment. For monitoring treatment of a prolactinoma or medication effects, doctors may repeat the test every few months.
Are there lifestyle factors that influence prolactin?
Sleep quality, stress and intense exercise can temporarily affect prolactin levels. It’s important to follow pre-test instructions to avoid false readings.
Can prolactin levels fluctuate during the day?
Yes. Prolactin levels are highest in the early morning and can vary after meals, stress or physical activity. That’s why testing is usually done a few hours after waking.
Can prolactin testing detect pituitary tumors?
Prolactin testing can indicate the possibility of a prolactinoma if levels are significantly elevated. Additional imaging, like an MRI, is used to confirm the diagnosis.