Alpha Subunit, Free, Serum/Plasma — Concentration
Measures the concentration of free glycoprotein hormone alpha subunit in blood, which can reflect pituitary hormone production.
["This blood test can help evaluate pituitary hormone production, sometimes in the care of a suspected pituitary tumor."]
Key facts at a glance
- LOINC
- 42234-5
- Short code
- Alpha subunit free SerPl-aCnc
- Synonyms
- Alpha subunit free SerPl-aCnc
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Critical range
- — – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84075
- SNOMED
- 27550007
- 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
What is this test?
This test measures free alpha subunit in serum or plasma. Alpha subunit is a shared component of several pituitary and pregnancy-related hormones, including thyroid-stimulating hormone, luteinizing hormone, and follicle-stimulating hormone.
Why might I need this test?
A clinician may order this test as part of an evaluation of pituitary hormone production, particularly when there are symptoms or other findings suggesting a pituitary condition. It is usually interpreted with other pituitary hormone tests and the results of an examination or imaging.
How is the test performed?
A blood sample is collected, and the laboratory measures the amount of free alpha subunit in the serum or plasma using a laboratory method. The free form refers to the portion not bound to other proteins.
How do I prepare for the test?
No special preparation is usually required. Follow any instructions from your clinician, and tell the laboratory if you are pregnant or taking hormone or other medicines that could affect the result.
Reference range
Adult: 44-147 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated free alpha subunit result may occur with increased production or secretion from a pituitary tumor, although other factors can also affect the level. A low result may reflect reduced pituitary hormone production. Results should be interpreted by a clinician alongside symptoms, other hormone measurements, and imaging when appropriate.
Short name
Free Alpha Subunit
Frequently asked questions
Is this the same as a standard pituitary hormone test?
Does pregnancy affect the result?
Does a normal result rule out a pituitary condition?
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