Thyroid Stimulating Hormone (TSH) with Serum/plasma Collection
This test measures the level of thyroid-stimulating hormone in your blood, which helps regulate your thyroid function.
["TSH helps your body maintain healthy thyroid hormone levels for energy, metabolism, and overall well-being."]
Key facts at a glance
- LOINC
- 12943-7
- Short code
- TSH sp4 p chal SerPl-aCnc
- Synonyms
- TSH sp4 p chal 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
- 84443
- SNOMED
- 301343003
- 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 healthcare provider 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 or after thyroid surgery. Sometimes, it’s part of a routine checkup or screening for conditions affecting metabolism.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider. Wear comfortable clothing for a simple blood draw. If you’re pregnant, have a medical condition, or are on certain medications, let your provider know beforehand.
What Happens During the Test?
A healthcare professional will draw a small amount of blood from a vein in your arm using a needle. The blood is collected in a test tube and sent to a lab for analysis. The process takes about 15 minutes, and you may feel slight discomfort, but it’s usually over quickly.
What Are Possible Results?
Results are interpreted by your healthcare provider based on your symptoms, medical history, and other tests. High TSH levels may suggest hypothyroidism, while low levels could indicate hyperthyroidism or other conditions. Your provider will discuss the meaning of your specific result with you.
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.
TSH is a key marker for thyroid health. Low or high levels can signal thyroid dysfunction, which may affect energy, digestion, weight, mood, and more. It’s often the first test used to diagnose thyroid disorders, especially in cases where symptoms like fatigue, weight changes, or hair loss are present.
Short name
TSH
Frequently asked questions
What Does a TSH Test Measure?
How Long Does It Take to Get Results?
Can I Eat or Drink Before the 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