Free Alpha Subunit, Serum/Plasma — Concentration
Measures the concentration of the free alpha-subunit portion of a protein hormone in serum or plasma.
["This test measures a free hormone component and is best interpreted with the related hormone results and your clinician's assessment."]
Key facts at a glance
- LOINC
- 100835-8
- Short code
- Alpha subunit free sp6 p chal SerPl-aCnc
- Synonyms
- Alpha subunit free sp6 p chal 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?
A free alpha subunit is the unbound portion of the alpha component of certain protein hormones. This test measures its concentration in a blood sample after the laboratory separates serum or plasma from the blood.
Why might I need this test?
Free alpha-subunit measurements may be ordered to help evaluate hormone production or activity, track changes over time, or supplement results for the complete hormone. The reason for testing depends on the specific hormone identified on your laboratory report.
How is the test performed?
A blood sample is drawn from a vein and processed into serum or plasma. The laboratory then measures the free alpha-subunit concentration using a validated assay.
How do I prepare for the test?
Special preparation is often not required, but follow the instructions provided by the laboratory. If the test is part of a challenge or timed collection, the exact timing and any preceding dose or procedure are important.
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 abnormal free alpha-subunit level may reflect changes in the production, release, or clearance of the hormone from which it comes. Results should be interpreted with the complete hormone measurement, symptoms, medical history, and the laboratory's reference interval. This result alone does not establish a diagnosis.
Short name
Free alpha subunit
Frequently asked questions
What does “free” mean in this test?
Can this test determine whether I am pregnant?
Why is my result interpreted with other hormone tests?
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