Serum or Plasma Thyroid-Stimulating Hormone (TSH) Measurement
This test measures the level of TSH, a hormone produced by your pituitary gland that regulates thyroid function. It helps assess whether your thyroid is working properly.
["TSH helps determine if your thyroid is underactive, overactive, or functioning normally."]
Key facts at a glance
- LOINC
- 105758-7
- Short code
- Mtb mabA ethionmde res mut Islt/S
- Synonyms
- Mtb mabA ethionmde res mut Islt/S
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- 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 a TSH test to check for thyroid problems, such as hypothyroidism (low thyroid activity) or hyperthyroidism (high thyroid activity). It’s often the first test recommended for thyroid function evaluation, especially if you have symptoms like fatigue, weight changes, or mood issues.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re taking thyroid medication, check with your doctor first to see if you should stop or adjust it before testing.
What the Results Mean
TSH results help guide treatment. Low TSH levels may indicate an overactive thyroid, while high levels suggest an underactive thyroid. Normal results usually fall within a specific range, but your doctor will interpret results in the context of your overall health and symptoms.
Common Reasons for Testing
TSH testing is commonly done if you have symptoms like unexplained weight changes, fatigue, depression, or hair loss. It’s also used to monitor thyroid function after treatment for thyroid disorders or during pregnancy.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: TSH’s Role in Health
Short name
TSH (Thyroid-Stimulating Hormone)
Frequently asked questions
What are the normal reference ranges for this test?
Can I eat or drink before this test?
Will this test affect my thyroid medication?
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