: Prolactin 24-Hour Urine Excretion Rate
: This test measures the amount of prolactin, a hormone made by the pituitary gland, released in urine over a full 24-hour collection period and expresses the result as an excretion rate.
[": A 24-hour urine prolactin rate can support evaluation of pituitary hormone production, but it is not a standard first-line test and is interpreted alongside blood prolactin levels."]
Key facts at a glance
- LOINC
- 21380-1
- Short code
- Prolactin 24h Ur-mRate
- Synonyms
- Prolactin 24h Ur-mRate
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 2
- Ref high
- 18
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84146
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
: What Is Prolactin?
: Prolactin is a hormone produced mainly by the pituitary gland, a small gland at the base of the brain. It plays a key role in breast development and milk production, and its levels are normally regulated by other hormones and signals from the brain.
: How the 24-Hour Urine Test Works
: Instead of a single blood draw, this test collects all urine produced over 24 hours. Measuring how much prolactin leaves the body in urine over a full day gives an estimate of hormone output that is less affected by short-term fluctuations than a single blood sample.
: Why It Might Be Ordered
: A clinician may request this test as part of an evaluation of suspected pituitary or hormonal disorders, such as unusual milk production, missed or irregular periods, or concerns about pituitary tumors. It is generally used in addition to, not instead of, standard blood prolactin testing.
: Preparing for the Collection
: Follow your laboratory's instructions for the 24-hour collection, which usually means discarding the first morning urine and then saving every urination for the next 24 hours. Mention any medications, stress, or recent procedures, since these can influence prolactin levels.
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.
: Prolactin measurement helps assess pituitary function and can be relevant to evaluating conditions such as prolactinoma, infertility, menstrual disturbances, and abnormal breast milk production. Urine prolactin testing is less established than serum testing, so results should be interpreted by a clinician in the context of symptoms, medications, and other hormone tests.
Short name
: 24-Hour Urine Prolactin
Frequently asked questions
: Is a 24-hour urine prolactin test routine?
: Do I need to fast or avoid activity before collecting urine?
: Can medicines change my result?
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