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Prolactin by Immunoassay (Serum)

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

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

Quick summary

["Prolactin levels can help diagnose hormonal imbalances or conditions like hyperprolactinemia."]

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

Key facts at a glance

LOINC
50519-8
Short code
Prolactin sp3 SerPl-mCnc
Synonyms
Prolactin sp3 SerPl-mCnc
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 a serum prolactin test to check for conditions such as pituitary tumors, thyroid disorders, or issues with breast milk production. It can also be used to monitor treatment for hormonal imbalances or symptoms like infertility or irregular menstrual cycles.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if instructed. Wear comfortable clothing and plan to stay for about 15 minutes while a blood sample is drawn.

What Happens During the Test?

A healthcare professional will insert a small needle into a vein in your arm or hand to collect a blood sample. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis using an immunoassay method.

What Are Possible Results?

Results are reported as a concentration of prolactin in the blood, measured in nanograms per milliliter (ng/mL). Your results will be compared to reference ranges provided by your healthcare provider based on your age, sex, and health status.

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

Serum Prolactin

Frequently asked questions

What causes abnormal prolactin levels?
Abnormal prolactin levels can result from medical conditions (e.g., tumors in the pituitary gland), medications (e.g., antidepressants, antipsychotics), or hormonal imbalances. Stress, pregnancy, or breastfeeding can also temporarily affect levels.
How often should I get this test?
Your doctor will determine how often you need this test based on your symptoms, medical history, and treatment plan. Follow-up tests may be scheduled if initial results are outside the expected range or if symptoms persist.
Can lifestyle changes affect prolactin test results?
Yes, certain activities like exercise, stress, or sexual arousal can temporarily raise prolactin levels. Avoid these factors before your test if instructed by your provider to get the most accurate 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