Serum Prolactin Level by Immunoassay (Confirmatory)
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.
Prolactin levels can signal potential hormonal imbalances or conditions affecting your reproductive or thyroid health.
Key facts at a glance
- LOINC
- 33908-5
- Short code
- Prolactin 1.5h p 200ug TRH IV SerPl-sCnc
- Synonyms
- Prolactin 1.5h p 200ug TRH IV SerPl-sCnc
- 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 irregularities, or other symptoms. It may also be used to monitor treatment for conditions like pituitary tumors or thyroid disorders.
What to Expect Before the Test
No special preparation is needed, but you may be asked to avoid certain medications (like certain antidepressants or antipsychotics) that could affect results. If you’re breastfeeding, let your provider know, as prolactin levels may be measured for monitoring milk production.
During the Test
A blood sample will be taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The sample is then sent to a lab for analysis using an immunoassay method to detect prolactin.
What the Results Mean
Results are compared to a reference range, but since ranges can vary by lab, your provider will interpret them in the context of your symptoms and medical history. High levels may indicate pituitary issues, while low levels could suggest hypothyroidism or other conditions.
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 lead to symptoms like missed periods, reduced fertility, or galactorrhea (milk production outside breastfeeding). Low levels may signal thyroid dysfunction or other hormonal imbalances. Always discuss results with your doctor for personalized guidance.
Short name
Prolactin
Frequently asked questions
Will this test affect my medications?
Can I still breastfeed if my prolactin level is high?
How often will I need this test?
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