Thyroid Stimulating Hormone (TSH) with Serum Preparation
This blood test measures the amount of thyroid-stimulating hormone (TSH) in your serum. TSH helps regulate your thyroid gland’s activity, which affects metabolism, energy levels, and overall health.
["TSH helps doctors check if your thyroid is working properly."]
Key facts at a glance
- LOINC
- 65360-0
- Short code
- TSH pre/p chal SerPl-aCnc
- Synonyms
- TSH pre/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 This Test Is Done
Your doctor may order this test to diagnose or monitor thyroid disorders, such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). It’s often the first test used to check thyroid function because TSH levels can be sensitive indicators of thyroid issues.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before drawing blood to ensure accurate results. Wear comfortable clothing and plan to stay near the testing site for a short time.
What Happens During the Test
A healthcare provider will insert a small needle into a vein in your arm to draw blood. You may feel a slight pinch, but it usually takes only a few minutes. The blood sample is then sent to a lab for analysis.
What the Results Mean
TSH results help determine whether your thyroid is producing too much or too little hormone. Abnormal levels may signal the need for further testing or treatment, such as medication or thyroid hormone replacement.
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.
Elevated TSH levels often indicate hypothyroidism, while low TSH levels may suggest hyperthyroidism or other thyroid disorders. It’s a critical test for early detection and management of thyroid-related conditions, which can impact energy, weight, and mood.
Short name
TSH Screening
Frequently asked questions
How long does it take to get my TSH results?
Can I eat or drink before this test?
What if my TSH level is outside the normal range?
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