Thyroid-stimulating hormone (TSH) with serum/plasma concentration measurement
This test measures the amount of thyroid-stimulating hormone (TSH) in your blood. TSH is a hormone produced by your pituitary gland that regulates thyroid function.
["TSH helps your body maintain healthy thyroid hormone levels."]
Key facts at a glance
- LOINC
- 34054-7
- Short code
- TSH pre/p TRH SerPl-aCnc
- Synonyms
- TSH pre/p TRH SerPl-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.4
- Ref high
- 4
- Critical range
- 0.1 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- 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
Why Is This Test Done?
Your doctor may order a TSH test to check for thyroid problems, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). It can also be used to monitor thyroid function during treatment for thyroid disorders or after thyroid surgery.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Avoid smoking, caffeine, or strenuous activity for a few hours before testing.
How the Test Is Performed
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick and usually painless. The blood sample is sent to a lab for analysis.
What the Results Mean
TSH results alone don’t provide a full picture—your doctor will consider them alongside other tests, symptoms, and medical history. Abnormal results may signal thyroid dysfunction, but further evaluation is needed.
Reference range
Adult: 0.4-4.0 mIU/LN/A
Take your thyroid medication after the blood draw if applicable. No fasting required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: TSH’s Role in Diagnosing Thyroid Disorders
Short name
TSH Level
Frequently asked questions
How often will I need this test?
What are typical reference ranges for TSH?
Can lifestyle changes affect TSH test results?
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