Thyroid Stimulating Hormone (TSH) with Plasma Specimen Measurement
This test measures the level of thyroid-stimulating hormone (TSH) in your blood plasma, which helps your doctor assess thyroid function.
["TSH helps regulate your metabolism and is key to diagnosing thyroid disorders."]
Key facts at a glance
- LOINC
- 47953-5
- Short code
- TSH pre dose LRH IV SerPl-aCnc
- Synonyms
- TSH pre dose LRH IV 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 doctor may order this test to check for thyroid problems, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). It’s often used as part of routine check-ups or when symptoms like fatigue, weight changes, or mood swings appear.
What Does a TSH Test Measure?
TSH is a hormone produced by your pituitary gland that signals your thyroid to produce thyroid hormones (like thyroxine, or T4). Abnormal TSH levels can indicate whether your thyroid is working too slowly or too quickly.
How Is the Test Performed?
A blood sample is taken from a vein in your arm, usually in a doctor’s office or lab. The blood is then sent to a lab where it’s analyzed for TSH levels using a sensitive immunoassay method.
What Are Common Results and Next Steps?
If your TSH is too high, it may suggest hypothyroidism. If it’s too low, it could indicate hyperthyroidism. Your doctor will interpret results in relation to your symptoms and may recommend further tests, like checking thyroid hormone levels (T4 or free T4) if 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 plays a central role in thyroid health. Elevated TSH often points to hypothyroidism, while low TSH may signal hyperthyroidism or other conditions like pituitary disorders. Early detection helps manage symptoms and prevent long-term complications.
Short name
TSH Plasma
Frequently asked questions
How long does it take to get my TSH test results?
Can I eat or drink anything before this test?
What are the most common symptoms of thyroid issues that might lead to this 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