Thyroglobulin Levels
- Sample Type
- Serum
- Fasting
- No
- Unit
- ng/mL
Function
Thyroglobulin (Tg) is a large glycoprotein produced exclusively by the follicular cells of the thyroid gland. It serves as a substrate for the synthesis of the thyroid hormones T3 and T4. Because it is only produced by thyroid tissue, it acts as a highly specific 'tumor marker' in individuals who have undergone treatment for thyroid cancer.
Why it is Ordered
The primary use of this test is the post-operative monitoring of patients with differentiated thyroid cancer (Papillary or Follicular). After the thyroid gland is surgically removed (thyroidectomy) and any remaining tissue is ablated with radioactive iodine, thyroglobulin levels should ideally be undetectable. A rise in Tg indicates the recurrence or persistence of thyroid tissue/cancer.
Associated Conditions
- Differentiated Thyroid Cancer: Used for surveillance of recurrence.
- Graves' Disease: Can cause elevated Tg due to hyperstimulation of the gland.
- Thyroiditis: Inflammation causes the 'leakage' of Tg into the bloodstream.
- Goiter: Benign enlargement of the thyroid increases the mass of Tg-producing cells.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
The presence of Thyroglobulin Antibodies (TgAb) is the most significant confounding factor; these antibodies can bind to Tg and cause false-low or false-high results depending on the laboratory method used. Additionally, high doses of Biotin (Vitamin B7) can interfere with the immunoassay, leading to inaccurate results. Patients should always have their TgAb levels measured simultaneously. If results are unexpected, a second opinion using a different assay method (like LC-MS/MS) is recommended.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for Thyroglobulin Levels:
Official Sources
Research & Guidelines
- PubMed: Thyroglobulin Levels Clinical GuidelinesNCBI / PubMed
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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