Prolactin Blood Test Levels: Normal Ranges and Results

A prolactin blood test measures the amount of prolactin in the blood to check for hormone imbalances.

Men and women of all ages need prolactin in balance to support metabolism, immune health, and reproductive function. Low prolactin and high prolactin can indicate anything from pituitary tumors to medication side effects or metabolic disorders that put you at risk for disease.

To make sense of your prolactin test results, you’ll want to know what’s normal for your sex, age and during pregnancy.

What is a Normal Prolactin Level?

Your prolactin reference range depends on your sex, whether you’re pregnant, your age, and even what time of day you get tested. Lab methods also affect the numbers you see on your results.

Most laboratories define the upper normal limit between 15-25 ng/mL for adults.

Normal Ranges for Adults

Population	Normal Range	Typical Average
Men	Less than 20 ng/mL	~5 ng/mL
Nonpregnant women	Less than 25 ng/mL	~13 ng/mL
Pregnant women	80-400 ng/mL	Up to 500 ng/mL

The Canadian Medical Association offers practical guidance for primary care:^[1]

“Normal prolactin levels are less than 25 μg/L in females and less than 20 μg/L in males. Measurement is indicated for erectile or ejaculatory dysfunction in males, as well as infertility, low libido, or galactorrhea outside pregnancy or nursing.”

Prolactin Levels During Pregnancy

Prolactin rises steadily throughout pregnancy as your body prepares for breastfeeding. The increases are dramatic.

Trimester	Mean Prolactin Level
First trimester	~16 ng/mL
Second trimester	~49 ng/mL
Third trimester	~113 ng/mL

Levels can reach up to 500 ng/mL by delivery. This is completely normal and prepares your breasts for milk production.

Normal Levels in Children

Children have lower prolactin levels than adults. The ranges shift as kids grow into their teenage years.

Age Group	Male Range	Female Range
Infants (0-1 year)	3-25 ng/mL	3-25 ng/mL (newborn girls 0-1 month: 1-90 ng/mL)
Children (1-10 years)	3-20 ng/mL	3-20 ng/mL
Teen boys (11-19 years)	3-16 ng/mL	—
Teen girls (11-19 years)	—	4-30 ng/mL

Newborn girls can show higher levels in their first month due to exposure to maternal hormones.

How Prolactin Changes During Your Menstrual Cycle

Your prolactin levels fluctuate throughout your cycle. The changes are moderate but measurable.

• Follicular phase: 12.1 µg/L
• Luteal phase: 13.9 µg/L
• Mid-cycle: 17 µg/L

Peak levels happen mid-cycle around ovulation. These variations are normal and don’t require treatment.

Prolactin also declines with age in men. A 21-year-old averages 9.2 µg/L, while a 61-year-old averages 6.9 µg/L.

What Do High Prolactin Levels Mean?

High levels of prolactin (hyperprolactinemia) disrupt your reproductive system and can signal a pituitary tumor. The severity depends on how high your levels climb.

Doctors classify hyperprolactinemia into three categories based on your test results:

• Physiologic
• Pharmacologic
• Pathologic

Understanding Hyperprolactinemia Severity

Level	Interpretation
33-94 ng/mL	Mild hyperprolactinemia
94-236 ng/mL	Significant hyperprolactinemia
>236 ng/mL	Severe hyperprolactinemia

A level above 250 µg/L usually means you have a prolactinoma (a prolactin-producing pituitary tumor). Levels above 500 µg/L are diagnostic of a macroprolactinoma (a large tumor over 1 cm).^[2]

Most non-tumor causes won’t push your prolactin above 200 ng/mL. Higher numbers point to a pituitary problem that needs imaging.

Symptoms of High Prolactin

The symptoms differ between men and women, but both sexes experience reproductive problems.

In women:

• Irregular or absent periods
• Milk production when not pregnant or nursing (galactorrhea)
• Infertility and trouble conceiving
• Vaginal dryness during sex
• Decreased sex drive
• Acne and excess facial or body hair

In men:

• Erectile dysfunction
• Decreased sex drive and interest in sex
• Infertility and low sperm count
• Decreased body and facial hair
• Enlarged breast tissue (rare)

From pituitary tumors in both sexes:

• Persistent headaches
• Vision problems or loss of peripheral vision
• Other hormone deficiencies if the tumor affects nearby hormone-producing cells

These symptoms develop because prolactin interferes with estrogen in women and testosterone in men.

What Causes Elevated Prolactin?

High prolactin comes from three main sources: natural body processes, pituitary or brain problems, or medications.

Normal physiological causes:

• Pregnancy and breastfeeding (the most common cause)
• Sleep (levels rise during sleep)
• Stress and anxiety
• Vigorous exercise
• Nipple stimulation including from sex
• Eating (mild increases after meals)

Disease-related causes:

• Prolactinomas (most common pathological cause)
• Other pituitary tumors that compress the stalk
• Hypothyroidism (low thyroid function)
• Kidney failure
• Liver disease
• Chest wall injuries or surgery

Medication-induced hyperprolactinemia is the most common cause of elevated prolactin outside of pregnancy. We’ll cover this in detail below.

What Do Low Prolactin Levels Mean?

Low prolactin (hypoprolactinemia) gets less attention than high levels, but it causes real problems. Men with low prolactin face higher risks of diabetes and heart disease.

Medical guidelines define hypoprolactinemia as levels below 3 µg/L in women and 5 µg/L in men.

Symptoms of Low Prolactin

The symptoms vary by sex and can be subtle.

In women:

• Inability to produce breast milk after childbirth (agalactia)
• Irregular menstrual periods
• Difficulty getting pregnant
• Fatigue and low energy
• Mood changes and depression

In men:

• Erectile dysfunction
• Reduced sperm count and sperm movement
• Decreased body and facial hair
• Depression and anxiety
• Increased risk of diabetes and heart disease

Research on European men aged 40-86 found that prolactin levels below 3 ng/mL predicted type 2 diabetes risk. The cardiometabolic effects are real and measurable.^[3]

Causes of Low Prolactin

Several conditions can suppress prolactin production:

• Hypopituitarism (underactive pituitary gland)
• Excessive treatment with dopamine agonist medications
• Sheehan syndrome (pituitary damage after childbirth bleeding)
• Growth hormone deficiency
• Pituitary radiation or surgery damage
• Rare genetic mutations affecting prolactin production

Low prolactin often signals broader pituitary problems that affect multiple hormones.

How the Prolactin Blood Test Works

The prolactin blood test is straightforward. A healthcare worker draws blood from a vein in your arm, and the lab measures your prolactin concentration.

No special preparation is needed for most people.

Best Time to Test

Timing matters because prolactin follows a daily rhythm. Your levels peak between 4 AM and 7 AM during early morning sleep.

The ideal time to test is 3-4 hours after waking in the morning. This catches your levels after they’ve dropped from the early morning peak but before daily activities affect them.

You can get tested any time of day if needed. Just know that timing affects your results, which is why your doctor might retest you at the same time of day.

Do You Need to Fast?

Fasting is not required for a prolactin test. You can eat and drink normally before your blood draw.

Some doctors might ask you to fast for 9-12 hours if your first test shows elevation. This helps confirm the diagnosis and rules out temporary increases from meals.

The blood draw itself should be quick and stress-free. Stress from a difficult blood draw can temporarily raise your prolactin levels and give false results.^[2]

What Can Affect Your Prolactin Test Results?

Many factors beyond disease states can change your prolactin levels. Understanding these helps you and your doctor interpret results correctly.

Multiple factors can temporarily raise your prolactin without indicating a health problem.

Everyday Factors That Raise Prolactin

Your daily activities and body states influence prolactin release:

• Sleep patterns
• Stress and anxiety
• Physical exercise
• Nipple stimulation
• Sexual activity
• Recent meals

These are normal responses. They’re why doctors often retest if your first result is mildly elevated.

Medications That Increase Prolactin

Drug-induced hyperprolactinemia is the most common cause of elevated prolactin in people without pituitary tumors. Some medications have dramatic effects.^[4]

Drug Class	Examples	Effect on Prolactin
Typical antipsychotics	Haloperidol, phenothiazines, fluphenazine	2-10x increase; 40-90% of users develop high prolactin
Atypical antipsychotics	Risperidone (80-100% affected), paliperidone	Most common medication cause overall
Antiemetics	Metoclopramide, domperidone	5-fold increase in healthy people
SSRIs	Fluoxetine, sertraline, citalopram	8-fold increased risk of milk production
Tricyclic antidepressants	Amitriptyline, clomipramine	Rarely cause problems
Blood pressure drugs	Verapamil (8.5% affected), methyldopa, reserpine	Variable effects
Opioids	Methadone, morphine	Temporary increase after dosing
Estrogens	High-dose oral contraceptives	Less than 1% with modern low-dose pills

Drug-induced increases rarely push prolactin above 118 ng/mL. Levels up to 280 ng/mL occasionally happen, but higher numbers suggest a tumor rather than medication effects.

Risperidone and metoclopramide deserve special mention. These drugs can raise prolactin above 200 ng/mL in people without pituitary adenomas.^[2]

Medications That Decrease Prolactin

Some medications lower prolactin levels:

• Dopamine agonists (bromocriptine, cabergoline, pergolide) — used to treat high prolactin
• Amphetamines and stimulants — through dopamine release
• Certain epilepsy medications

These are less common causes of abnormal results.

Macroprolactinemia: When High Levels Don’t Mean Much

Macroprolactinemia shows up in almost 20% of blood samples with elevated prolactin. This condition sounds scary but usually isn’t.

Macroprolactin is a form of prolactin that’s bound to antibodies. These large complexes have low biological activity, meaning they don’t cause typical symptoms even though your total prolactin appears high.^[5]

You might show elevated prolactin on paper but have no milk production, no menstrual problems, and no fertility issues. That’s macroprolactinemia.

Most people with macroprolactinemia don’t need treatment. Your doctor can screen for it using an inexpensive test called polyethylene glycol (PEG) precipitation.

The Hook Effect

The hook effect is a rare lab problem that makes very high prolactin look falsely low. It happens with giant pituitary tumors (usually over 4 cm).

When prolactin is extremely high, it can overwhelm the lab test and produce falsely low results in the 30-120 ng/mL range. The tumor is huge, but the lab report shows moderate elevation.

Your doctor should suspect this when you have a large pituitary mass on MRI but unexpectedly low prolactin. They’ll rerun the test with your blood sample diluted 1:100 to get the true value.^[2]

When to Repeat Testing

Not every elevated result needs extensive workup. The degree of elevation and your symptoms guide next steps.

Mildly elevated results (20-40 ng/mL) should be confirmed with at least two tests on different days. Prolactin varies throughout the day and can spike temporarily.

Markedly elevated levels (more than 5 times the upper normal limit) are reliable. A single test is enough to diagnose hyperprolactinemia.

If you have high prolactin but no symptoms, your doctor should screen for macroprolactin before ordering expensive imaging or starting treatment.

What Your Doctor Will Do Next

For elevated prolactin, your doctor will:

1. Rule out pregnancy
2. Check thyroid function
3. Review all medications
4. Test kidney and liver function
5. Screen for macroprolactin
6. Order pituitary MRI

For low prolactin, expect testing for other pituitary hormones to check overall pituitary function.

The Bigger Picture

Your prolactin level is one piece of your hormone health puzzle. Understanding the normal ranges for your situation helps you interpret results without panic.

Most mildly elevated results come from stress, medications, or normal body processes. Levels above 250 ng/mL demand attention and imaging.

Low prolactin matters more than doctors once thought, especially for men’s metabolic health. Testing other pituitary hormones reveals whether low prolactin signals broader endocrine problems.

“Prolactin testing exemplifies precision medicine,” says Dr. Jin-Xiong She, founder of Jinfiniti Precision Medicine. “A single biomarker, interpreted correctly within the right clinical context, can reveal problems ranging from medication effects to serious pituitary disease. The key is knowing what the numbers mean for each individual patient.”

Track your prolactin over time if you’re treating high or low levels. Serial testing shows whether your treatment works and helps your doctor adjust your care.

At Jinfiniti, our AgingSOS Ultimate Panel includes prolactin testing along with 47+ other biomarkers that measure everything from your hormone balance and metabolic health to your cellular aging rate. Testing prolactin along with your other hormones can identify patterns that may go unnoticed when looking at a single test.