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Free Alpha Subunit, Serum/Plasma — Mass Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures the free alpha subunit released by pituitary glycoprotein hormones in a blood sample to help evaluate certain pituitary conditions.

Quick summary

["This blood test measures free pituitary alpha subunit, which may be elevated in some pituitary tumors."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
30316-4
Short code
Alpha subunit free SerPl-mCnc
Synonyms
Alpha subunit free SerPl-mCnc
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 free alpha subunit produced by the pituitary gland. This subunit is shared by several pituitary hormones, including follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone.

Why might I need this test?

The test may be ordered when a pituitary tumor or another pituitary condition is suspected. It is usually interpreted with other pituitary hormone measurements and clinical findings.

How is the test performed?

A blood sample is collected and analyzed in the laboratory to determine the concentration of free alpha subunit. The exact laboratory method may vary.

How do I prepare for the test?

No special preparation is usually required. Follow any instructions from your healthcare professional, and tell the laboratory if you are pregnant, taking hormone medications, or recently received hormone treatment.

Reference range

Adult: 44-147 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Alpha Subunit Test

Frequently asked questions

Does a high result mean I have cancer?
No. A high result can occur with several pituitary conditions and does not by itself establish cancer. Your clinician will interpret it with your symptoms, examination, and other laboratory results.
Why are other pituitary hormone tests needed?
Free alpha subunit is shared by several pituitary hormones, so related hormone measurements help determine whether the result reflects a specific pituitary disorder.
Can medications affect the result?
Yes. Hormone medications, pregnancy, and some medical conditions can influence pituitary hormone measurements. Tell your healthcare team about relevant medications and medical history.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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