Thyroid Stimulating Hormone (TSH) with Serum Specimen
This test measures the level of thyroid-stimulating hormone in your blood, which helps your thyroid gland produce hormones that regulate metabolism, energy, and other bodily functions.
["TSH helps diagnose thyroid disorders and guides treatment for conditions like hypothyroidism or hyperthyroidism."]
Key facts at a glance
- LOINC
- 50537-0
- Short code
- TSH sp5 SerPl-aCnc
- Synonyms
- TSH sp5 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 This Test Matters
Your doctor may order a TSH test if you have symptoms like fatigue, weight changes, or unexplained issues with your metabolism. It’s also used to monitor thyroid hormone levels during treatment for thyroid conditions.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a fasting panel. Bring any medications you’re currently taking to your appointment.
What the Test Involves
A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab for analysis using an immunoassay method to measure TSH levels.
Possible Results and Next Steps
Results are typically reported in microinternational units per liter (µIU/L). Low TSH may indicate hyperthyroidism, while high TSH often signals hypothyroidism. Your doctor will discuss results with you and may recommend further testing 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 is a critical marker for thyroid function. It’s the most sensitive test for detecting thyroid dysfunction, often used as the first line in diagnosing conditions like Hashimoto’s disease or Graves’ disease. Abnormal levels can guide treatment adjustments, such as medication dosing or thyroid replacement therapy.
Short name
TSH
Frequently asked questions
What causes TSH levels to be abnormal?
How long does it take to get results?
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