Serum Prolactin Level (15-Minute Post-Rapid-Acting Thyroid Hormone Stimulation)
This test measures your prolactin hormone level after receiving a small dose of thyroid-stimulating hormone (TSH) to check if your pituitary gland is functioning normally. Prolactin is a hormone that helps regulate breast milk production and affects other body functions.
["Assessing how your pituitary responds to TSH stimulation can help diagnose conditions like hyperprolactinemia or pituitary tumors."]
Key facts at a glance
- LOINC
- 48120-0
- Short code
- Prolactin 15M pre TRH IV SerPl-mCnc
- Synonyms
- Prolactin 15M pre TRH IV 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 This Test Is Done
Your doctor may order this test if they suspect a pituitary disorder, such as a tumor or an overactive pituitary gland, which could be causing high prolactin levels. It can also help evaluate whether your thyroid hormones are affecting prolactin production.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for a few hours before the blood draw. On the day of the test, avoid smoking or consuming caffeine, as these can affect hormone levels.
What Happens During the Test
A healthcare provider will draw blood from a vein in your arm. You’ll feel a small pinch, but it should only take a few minutes. The blood sample will be sent to a lab for testing after receiving the TSH dose.
What the Results Mean
Results will compare your prolactin level before and after the TSH dose. Abnormal results may indicate issues with your pituitary gland’s ability to regulate prolactin or other hormonal imbalances.
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.
Clinical Significance: Prolactin and Pituitary Function
Short name
Prolactin Post-TSH Stim Test
Frequently asked questions
What causes high prolactin levels?
How often should I get this test?
Can I take my medications before the 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