Quick Facts
- Sample: Blood
- Fasting: No fasting required. Stop biotin consumption at least 72 hours prior to collection.
- Turnaround: 5-7 days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
This test measures two biomarkers: Thyroglobulin (Tg), measured by immunometric assay (IMA), and Thyroglobulin Antibody (TgAb). Thyroglobulin is a protein produced by thyroid tissue. In this test, it is used to help monitor for the presence of remaining or recurring thyroid tissue in patients who have had thyroid gland ablation through surgery, with or without radioactive treatment.
Thyroglobulin Antibody is an antibody directed against thyroglobulin, not a thyroid hormone. It is measured for two reasons: to identify samples where TgAb may interfere with accurate Tg measurement, and, when reported quantitatively, to serve as a surrogate tumor marker that can help track changes in tumor mass in certain patients with differentiated thyroid cancer. This test does not measure TSH, T3, T4, or any other thyroid hormone, and it does not provide a direct assessment of thyroid gland function.
Benefits
- Helps monitor for residual or recurrent thyroid tissue after ablation
- Identifies antibody interference that could affect Tg results
- Supports tracking of tumor marker trends over time
- Provides quantitative TgAb data for certain monitoring purposes
- Uses a simple blood draw with no fasting required
Who Is This Test For?
- People being monitored after thyroid gland ablation (surgery, with or without radioactive treatment)
- People previously treated for differentiated thyroid cancer
- People whose healthcare provider is tracking Tg levels over time
- People whose healthcare provider wants to check for TgAb interference
- People whose healthcare provider is monitoring tumor marker trends
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What is the purpose of this thyroid test?
This test measures Thyroglobulin (Tg) by immunometric assay (IMA) and Thyroglobulin Antibody (TgAb). It is intended to help a healthcare provider monitor for the presence of remaining or recurrent thyroid tissue in patients who have had thyroid gland ablation, and to identify TgAb interference that could affect Tg results. TgAb can also serve as a surrogate tumor marker for tracking changes in tumor mass in certain patients. This is not a comprehensive thyroid panel and does not directly assess overall thyroid function.
2. Who would benefit from this test?
This test is generally used by people who have had thyroid gland ablation, including those previously treated for differentiated thyroid cancer, and whose healthcare provider wants to monitor Tg levels, check for antibody interference, or track tumor marker trends over time.
3. When should I order this test?
You may consider this test as part of ongoing monitoring after thyroid gland ablation, or as directed by your healthcare provider to help track Tg levels, assess for TgAb interference, or follow tumor marker trends over time. This test is not intended to diagnose a condition or to serve as a complete thyroid assessment on its own.
4. How does this test differ from other thyroid tests?
This test reports two distinct measurements: Thyroglobulin, a protein measured directly by immunometric assay (IMA), and Thyroglobulin Antibody, an antibody measurement rather than a hormone measurement. It does not measure TSH, T3, T4, or other thyroid hormones, and it should not be treated as interchangeable with those tests. TgAb specifically helps identify possible interference with Tg results and, when quantitative, can serve as a surrogate tumor marker.
5. Do I need to fast before this test?
No fasting is required for this test. You should stop biotin consumption at least 72 hours prior to collection.
6. How quickly will I get results?
Results are generally available in 5-7 days. Results may take longer based on weather, holidays, or lab delays.
7. How do I interpret the results?
The meaning of your Tg and TgAb results depends on your individual history, including prior thyroid surgery or ablation, other treatments, and any other thyroid or endocrine test results. TgAb levels can affect how Tg results should be interpreted, so both values are often reviewed together. A single result should not be viewed as confirming or ruling out a particular condition on its own. Your healthcare provider is best positioned to interpret these results in the context of your overall health.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
8. What should I do if my results are abnormal?
If your results fall outside the expected range, discuss them with a qualified healthcare provider. They can help determine whether additional evaluation or testing is appropriate based on your individual situation. Do not stop prescribed medication unless instructed by your healthcare provider.
9. How often should I get tested?
Testing frequency should be determined as directed by your healthcare provider, based on your individual monitoring needs following thyroid ablation or treatment for differentiated thyroid cancer.
Pre-test preparation
No fasting is required for this test. Stop biotin consumption at least 72 hours prior to collection. Do not stop prescribed medication unless instructed by your healthcare provider.
