Thyroid-stimulating hormone (TSH) concentration in plasma
This test measures the amount of thyroid-stimulating hormone (TSH) in your blood plasma. TSH is a hormone produced by your pituitary gland that helps regulate your thyroid function.
["TSH helps your thyroid produce hormones that control metabolism and energy levels."]
Key facts at a glance
- LOINC
- 3018-9
- Short code
- Thyrotropin releasing horm Plas-mCnc
- Synonyms
- Thyrotropin releasing horm Plas-mCnc
- Category
- chemistry
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 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 This Test Might Be Ordered
Your healthcare provider may order this test to check for thyroid problems, such as hypothyroidism (when your thyroid doesn’t produce enough hormones) or hyperthyroidism (when it produces too much). It’s also used to monitor treatment for thyroid disorders or to screen for conditions like pituitary tumors.
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 it’s part of a more complex evaluation. Bring any medications you’re currently taking to your appointment.
What the Test Involves
A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it typically doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.
What the Results Mean
Results help determine whether your thyroid is functioning normally. Abnormal levels can signal underlying health issues that need further evaluation or treatment.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
TSH is a key marker for thyroid health. Low levels may indicate hyperthyroidism, while high levels often suggest hypothyroidism. It’s also useful for detecting early thyroid dysfunction before symptoms appear, such as fatigue, weight changes, or mood shifts.
Short name
TSH Plasma
Frequently asked questions
How often should I get this test?
What are typical reference ranges?
Can diet or medications 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