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Serum Prolactin Level

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of prolactin, a hormone produced by your pituitary gland, in your blood. Prolactin helps regulate breast milk production and affects other hormones in your body.

Quick summary

["Prolactin levels can help diagnose conditions related to hormone imbalances or pituitary gland issues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
78984-2
Short code
Macroprolactin/Prolactin % SerPl
Synonyms
Macroprolactin/Prolactin % SerPl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
2
Ref high
18
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84146
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for conditions like hyperprolactinemia (high prolactin levels), which can cause issues with fertility, menstrual problems, or other hormonal imbalances. It may also be used to evaluate symptoms such as galactorrhea (milk production outside of pregnancy), irregular periods, or unexplained headaches.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider. Bring any medications you’re currently taking, as some may affect results. Avoid smoking or consuming alcohol for a few hours before the blood draw.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch or discomfort, but it usually lasts only a few seconds. The blood sample will be sent to a lab for analysis.

What Are Possible Results?

Results are typically reported in nanograms per milliliter (ng/mL) or micrograms per liter (µg/L). Your provider will interpret the results in relation to your symptoms and medical history.

Reference range

Adult males: 2-18 ng/mL; Females: 2-29 ng/mLN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Prolactin

Frequently asked questions

What causes prolactin levels to be high?
High prolactin levels can be caused by conditions like pituitary tumors, certain medications (such as antidepressants or antipsychotics), thyroid problems, or kidney disease. Lifestyle factors like stress, smoking, or excessive exercise may also play a role.
How long does it take to get results?
Test results are usually available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you with the results and any follow-up recommendations.
Can I take my medications before the test?
Yes, you can take your usual medications as directed, but inform your healthcare provider beforehand. Some medications may affect prolactin levels, so they may adjust your treatment plan based on the test results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy