Thyroglobulin (serum/plasma) mass concentration
This test measures the amount of thyroglobulin, a protein produced by thyroid cells, in your blood. It’s often used to monitor thyroid cancer treatment or check for recurrence.
["A Tg test helps track thyroid health after treatment for thyroid cancer or thyroid disease."]
Key facts at a glance
- LOINC
- 100796-2
- Short code
- Thyroglob Fld-mCnc
- Synonyms
- Thyroglob Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 if you have thyroid cancer (such as papillary or follicular thyroid cancer), especially after treatment like surgery or radioactive iodine therapy. It can also help check for signs of cancer returning (recurrence) or spreading to other parts of the body. Sometimes, it’s used in people with thyroid nodules or autoimmune thyroid disease to assess protein levels indirectly.
How Is the Test Performed?
A blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it’s analyzed to measure thyroglobulin levels using a sensitive immunoassay method. No special preparation is needed, but you may be asked to avoid certain medications that could affect results.
What Do Results Mean?
Thyroglobulin levels can vary widely depending on your health status. High levels may suggest thyroid cancer or its return, while normal or low levels could indicate no active cancer. Your doctor will interpret results in the context of your medical history and other tests.
What Are Common Causes of Abnormal Results?
Elevated thyroglobulin can occur with thyroid cancer, thyroiditis (inflammation of the thyroid), or certain medications. Low levels may happen after treatment for cancer or in people with thyroid hormone deficiencies. Other conditions, like autoimmune diseases, can also influence results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Thyroglobulin tests play a key role in managing thyroid cancer by providing early detection of recurrence or progression. They’re particularly useful in follow-up care after treatment, helping doctors monitor long-term outcomes and guide further treatment if needed.
Short name
Thyroglobulin (Tg) test
Frequently asked questions
What does a ‘positive’ or ‘negative’ result mean on this test?
How often should I get this test?
Can diet or medications affect thyroglobulin levels?
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