Free Alpha-Subunit, Serum/Plasma — Concentration
A blood test that measures free pituitary alpha-subunit, often interpreted together with FSH and LH to evaluate hormonal activity.
["This test measures free alpha-subunit in blood and is most useful when interpreted alongside other pituitary or reproductive hormone results."]
Key facts at a glance
- LOINC
- 100836-6
- Short code
- Alpha subunit free sp7 p chal SerPl-aCnc
- Synonyms
- Alpha subunit free sp7 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?
This test measures the amount of free alpha-subunit in serum or plasma. Alpha-subunit is a protein component shared by several pituitary hormones, including FSH, LH, and TSH.
Why might I need this test?
It may be ordered when a healthcare professional is evaluating a suspected pituitary condition or an abnormality in reproductive hormone production. It is generally interpreted with FSH, LH, TSH, and other laboratory results rather than as a stand-alone test.
How is the test performed?
A blood sample is collected, and the laboratory measures free alpha-subunit using an immunoassay. The results may be reported as a concentration, with the units specified by the laboratory.
How do I prepare for the test?
No special preparation is usually required. Tell your healthcare professional if you are pregnant, taking hormones, or have had recent pituitary surgery, because these factors can affect the results.
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 level can occur with some pituitary or hypothalamic disorders, including certain pituitary tumors. Levels may also be influenced by pregnancy, hormonal treatment, and changes in pituitary function, so an abnormal result should be interpreted with symptoms and other hormone tests.
Short name
Free alpha-subunit
Frequently asked questions
Is this the same as a FSH or LH test?
Does an elevated result mean I have a pituitary tumor?
Can hormonal medications affect the 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