Prolactin, 15-Hour Post-Midnight Serum Concentration (Quantitative)
This test measures the amount of prolactin, a hormone produced by your pituitary gland, in your blood after a 15-hour fast. It helps diagnose conditions related to hormonal imbalances.
["Prolactin levels can affect fertility, milk production, and other hormonal functions."]
Key facts at a glance
- LOINC
- 47868-5
- Short code
- Prolactin 1.5h p MCP SerPl-aCnc
- Synonyms
- Prolactin 1.5h p MCP SerPl-aCnc
- 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 This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like irregular menstrual periods, infertility, breast pain, or unusual milk production. It could also be used to evaluate pituitary gland function or rule out conditions like hyperprolactinemia.
What to Expect Before the Test
You’ll need to fast for 15 hours before the test, meaning no food or drink (except water) after midnight the night before. Avoid caffeine and smoking during this period to ensure accurate results.
How the Test Is Performed
A blood sample will be drawn from a vein, usually in your arm, by a healthcare professional. The sample is then sent to a lab for analysis using an immunoassay method to measure prolactin concentration.
What the Results Mean
Results are compared to standard reference ranges for your age and sex. High prolactin levels may suggest issues like a pituitary tumor, while low levels might indicate thyroid problems or other hormonal disorders.
Reference range
Adult males: 2-18 ng/mL; Females: 2-29 ng/mLN/A
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.
Elevated prolactin levels can disrupt normal hormone function, leading to symptoms like menstrual irregularities, infertility, or galactorrhea (unusual milk secretion). Low levels may indicate thyroid disorders, such as hypothyroidism, or other pituitary or hypothalamic conditions. This test helps diagnose and monitor these conditions for appropriate treatment planning.
Short name
Prolactin Level (15-Hour Post-Midnight)
Frequently asked questions
What causes prolactin levels to be tested?
How long does it take to get the results?
Can I take anything for my prolactin levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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