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Thyroid Stimulating Hormone Alpha Subunit, Serum/Plasma — Mass Concentration

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

Measures the TSH alpha subunit in blood, usually as part of evaluating pituitary hormone production and certain pituitary tumors.

Quick summary

["This blood test measures part of TSH and is mainly used with other tests to evaluate pituitary function."]

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

Key facts at a glance

LOINC
45173-2
Short code
TSH Alpha SerPl-mCnc
Synonyms
TSH Alpha SerPl-mCnc
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
44
Ref high
147
Critical range
0.1 N/A – 20 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 the alpha subunit of thyroid-stimulating hormone (TSH) in serum or plasma. TSH is produced by the pituitary gland and helps the thyroid gland regulate hormone production.

Why might I need this test?

This test is usually ordered with complete TSH and other pituitary hormone measurements when evaluating unexplained hormone abnormalities or a possible pituitary condition. It is most useful when interpreted as part of a complete clinical and laboratory assessment.

How is the test performed?

A blood sample is collected, and the TSH alpha subunit is measured using a laboratory assay. The sample may be processed as serum or plasma according to the laboratory's testing method.

How do I prepare for the test?

No special preparation is usually required. Tell your clinician about medicines or supplements you take because certain thyroid and pituitary treatments can affect the results, and do not stop prescribed medication without guidance.

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

TSH alpha subunit

Frequently asked questions

Is this the same as a standard TSH test?
No. A standard TSH test measures the complete TSH hormone, while this test measures its alpha subunit. The two tests provide different information and may be used together.
Does an abnormal result mean I have a pituitary tumor?
No. Elevated levels can have several causes, including conditions other than a tumor. Your clinician will interpret the result alongside symptoms, other hormone tests, and possibly imaging.
Are reference ranges available for this test?
Reference intervals can vary by assay and laboratory, and some laboratories report this test only as part of a specialized workup. The laboratory's report or your clinician should be used for interpretation.
  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