Thyroid Stimulating Hormone (TSH) with Serum/Plasma Measurement by Immunoassay
This blood test measures your thyroid-stimulating hormone, a key hormone that helps regulate your metabolism and thyroid function.
["Your TSH level helps doctors check if your thyroid is working properly."]
Key facts at a glance
- LOINC
- 25990-3
- Short code
- TSH 30M p TRH IN SerPl-sCnc
- Synonyms
- TSH 30M p TRH IN SerPl-sCnc
- 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?
Doctors may order a TSH test to diagnose or monitor thyroid conditions, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). It can also be used during pregnancy, to check for thyroid issues in newborns, or as part of routine health screenings.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm, and a small amount of blood will be drawn. If you’re on thyroid medication, let your healthcare provider know before the test.
What the Results Mean
TSH results help determine whether your thyroid is producing enough hormone. High levels may suggest hypothyroidism, while low levels could indicate hyperthyroidism or other thyroid disorders. Your doctor will interpret results in relation to your symptoms and medical history.
Common Conditions This Test Helps Diagnose
This test is often used to diagnose or manage conditions like Hashimoto’s disease (an autoimmune thyroid disorder), Graves’ disease, pituitary disorders, or thyroid nodules. It can also help monitor treatment for thyroid conditions.
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 is a critical marker for thyroid function. Abnormal levels can signal underlying thyroid dysfunction, which may require further testing or treatment to restore balance and prevent complications like fatigue, weight changes, or heart issues.
Short name
TSH Level
Frequently asked questions
What causes a TSH test to be ordered?
How long does it take to get TSH test results?
Can I eat or drink before a TSH blood test?
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