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Serum Prolactin Mass Fraction (Mass Concentration) by Immunoassay

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 body functions, including hormones and mood.

Quick summary

["Prolactin levels may indicate conditions affecting your pituitary gland or hormone balance."]

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

Key facts at a glance

LOINC
51441-4
Short code
Macroprolactin/Prolactin MFr SerPl
Synonyms
Macroprolactin/Prolactin MFr 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 be caused by tumors, medications, or other health issues. It may also be used to diagnose or monitor pituitary disorders, infertility, or symptoms like irregular periods, galactorrhea (milk production outside breastfeeding), or headaches.

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 your provider specifies it. Wear comfortable clothing and plan to stay for about 15 minutes while a blood sample is drawn from a vein in your arm.

What Happens During the Test?

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

What Are Possible Results?

Results are reported as a concentration of prolactin in nanograms per milliliter (ng/mL). Your provider will interpret the results in relation to your symptoms and medical history. Abnormal results may trigger further testing or follow-up.

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 Does It Mean If My Results Are High?
Elevated prolactin levels may suggest conditions such as pituitary adenomas (benign tumors), certain medications (like antidepressants or antipsychotics), thyroid disorders, or kidney problems. High levels can cause infertility, irregular periods, or galactorrhea. Your provider will discuss next steps based on your symptoms and test results.
What Does It Mean If My Results Are Low?
Low prolactin levels are less common but may occur with pituitary damage, certain medications, or genetic conditions. Low levels could affect hormone balance, including fertility or lactation. Your provider will evaluate this in the context of your overall health and may recommend additional testing if needed.
How Often Should I Get This Test?
Your provider will determine the frequency of testing based on your medical history, symptoms, and treatment plan. Regular monitoring may be needed if you have a known pituitary disorder, take medications affecting prolactin, or experience recurring symptoms like headaches or infertility.
  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