Quantitative Thyroglobulin without TGAB

The Quantitative Thyroglobulin without TGAB test contains 1 test with 2 biomarkers.

Brief Description: The Quantitative Thyroglobulin without Thyroglobulin Antibodies (TGAB) test is a medical laboratory examination that measures the level of thyroglobulin in the blood without interference from thyroglobulin antibodies. Thyroglobulin is a protein produced by the thyroid gland, and its measurement can provide valuable insights into thyroid health and the presence of certain thyroid-related conditions.

Also Known As: Tg Test, Thyroglobulin Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is a Thyroglobulin test ordered?

Prior to the surgical excision of the thyroid gland for malignancy, a thyroglobulin test may be requested. Additionally, it is done after therapy is finished to see if any remaining thyroid tissue—whether healthy or cancerous—may have been left over. After surgery, it is frequently requested on a monthly basis to make sure the tumor has not returned or spread.

When a patient exhibits signs of hyperthyroidism and/or an enlarged thyroid gland and the doctor feels that the patient might be suffering from a thyroid condition like Graves disease or thyroiditis, the doctor may occasionally order a thyroglobulin test. When someone is receiving anti-thyroid drug treatment, it could be prescribed periodically to assess how well the medicine is working.

Rarely, it may be prescribed when a baby exhibits hypothyroidism-related symptoms.

When a person has irregular TSH and/or free T4 test results, symptoms of low or high thyroid hormone levels, or the appearance of a goiter, testing may be performed, especially if the reason is considered to be an autoimmune condition.

Hypothyroidism can produce a variety of symptoms, including:

  • Gaining weight
  • Fatigue
  • Skin that is dry
  • Hair loss
  • Cold intolerance
  • Constipation

Hyperthyroidism can produce symptoms such as:

  • Sweating
  • Heart rate that is quite fast
  • Anxiety
  • Tremors
  • Fatigue
  • Sleeping problems 
  • Sudden weight loss
  • Eyes that protrude

What does a Thyroglobulin blood test check for?

The thyroid gland makes the protein thyroglobulin. Thyroglobulin in the blood is measured by this test.

The thyroid gland creates hormones that aid in controlling how quickly the body burns through energy. It is a tiny, butterfly-shaped organ that rests flat against the windpipe in the throat. Thyroglobulin is produced and stored mostly in very tiny, ball-shaped structures called follicles.

T4 and T3 are derived from thyroglobulin. The pituitary hormone TSH stimulates the synthesis of these hormones as well as their release into the bloodstream.

All healthy people generate thyroglobulin, albeit its blood content is often quite low. Both benign and malignant illnesses result in an increase in thyroglobulin concentration. Therefore, it can be used to monitor patients with thyroid papillary and follicular cancer after diagnosis. On the one hand, it is a non-specific sign of a thyroid dysfunction.

Lab tests often ordered with a Thyroglobulin test:

When a Quantitative Thyroglobulin test is ordered, it's often part of a broader evaluation of thyroid function and cancer surveillance. Here are some tests commonly ordered alongside it:

  1. Thyroglobulin Antibody (Anti-Tg):

    • Purpose: To detect antibodies against thyroglobulin.
    • Why Is It Ordered: The presence of thyroglobulin antibodies can interfere with the interpretation of the thyroglobulin test, as they can cause falsely low thyroglobulin levels or variability in test results.
  2. Thyroid Stimulating Hormone (TSH):

    • Purpose: To measure the level of TSH, a hormone that stimulates the thyroid gland.
    • Why Is It Ordered: TSH levels can influence thyroglobulin levels. In the follow-up of thyroid cancer, TSH is often suppressed with medication to reduce the stimulus for cancer growth.
  3. Thyroid Function Tests:

    • Purpose: To assess the levels of thyroid hormones in the blood.
    • Why Is It Ordered: To evaluate thyroid function, especially in individuals receiving thyroid hormone replacement after thyroidectomy for cancer.
  4. Serum Calcium and Parathyroid Hormone (PTH):

    • Purpose: To measure calcium levels and PTH, which can be affected by thyroid surgery.
    • Why Is It Ordered: To assess for hypocalcemia and parathyroid gland function, as these can be complications of thyroidectomy.
  5. Blood Urea Nitrogen (BUN) and Creatinine:

    • Purpose: To assess kidney function.
    • Why Is It Ordered: To ensure proper kidney function before administering certain diagnostic tests (like contrast CT scans) or treatments.

These tests, when ordered alongside a Quantitative Thyroglobulin test, provide a comprehensive evaluation of thyroid cancer management and overall thyroid health. They are crucial for detecting thyroid cancer recurrence, assessing the effectiveness of treatment, and monitoring the thyroid function in affected individuals. The specific combination of tests will depend on the individual’s treatment history, current thyroid function, and clinical presentation.

Conditions where a Thyroglobulin test is recommended:

  1. Thyroid Cancer: This test is commonly used in monitoring patients with thyroid cancer, as rising thyroglobulin levels may indicate cancer recurrence.
  2. Thyroid Disorders: In cases of Graves' disease, goiter, or other thyroid conditions, this test can provide additional insights into thyroid function and health.

How does my health care provider use a Thyroglobulin test?

The main purposes of the thyroglobulin test are to monitor for recurrence and assess the efficacy of thyroid cancer treatment. The most prevalent kinds of thyroid cancer, the well-differentiated papillary and follicular thyroid tumors, typically do so, leading to elevated levels of thyroglobulin in the blood. However, thyroid malignancies do not always create thyroglobulin.

Prior to thyroid cancer treatment, thyroglobulin testing and a TSH test may be done to ascertain whether the malignancy is making thyroglobulin. If so, the test can be requested on a regular basis after treatment to check for cancer recurrence. To examine the change in concentration, several thyroglobulin levels may be ordered throughout time. The change frequently offers more details than just one value.

In some cases, thyroglobulin testing is required to evaluate the efficacy of treatment for illnesses like Graves disease and to help identify the origin of hyperthyroidism.

Rarely, the test may be required to distinguish between subacute thyroiditis and thyrotoxicosis factitia, as well as to identify the root cause of congenital hypothyroidism in infants.

To aid in the diagnosis and/or monitoring of an autoimmune thyroid condition, one or more of the following tests may be used:

  • Thyroid peroxidase antibody, an antibody that targets thyroid peroxidase enzyme in the thyroid gland, can be seen in Graves disease and Hashimoto thyroiditis.
  • Thyroglobulin antibody is an antibody that targets thyroglobulin, the thyroid hormone's storage form.

These tests may be conducted to determine the reason of an enlarged thyroid or other symptoms linked to low or high thyroid hormone levels. When other thyroid test findings, such as total or free T3, free T4, and/or TSH, indicate thyroid dysfunction, testing may be done as a follow-up.

A thyroid antibody test or several thyroid antibody tests may be conducted to see if a person with an autoimmune disorder is at risk of thyroid dysfunction. Disorders like systemic lupus erythematosus, rheumatoid arthritis, and pernicious anemia can cause this.

A thyroglobulin test may be used to monitor someone who is being treated for thyroid cancer. The thyroglobulin antibody test is utilized in this scenario to see if the antibody is present in the person's blood and will interfere with the thyroglobulin level test.

What do my thyroglobulin results mean?

In extremely little amounts, thyroglobulin is found in the blood of every healthy person.

Thyroglobulin may serve as a tumor marker if levels are initially high in a thyroid cancer patient who has been diagnosed with the disease.

After the surgical excision of the thyroid and/or after subsequent radioactive iodine treatments, thyroglobulin levels should be undetectable or extremely low. A person may still have some normal or cancerous remaining thyroid tissue in their body, necessitating further therapy, if the thyroglobulin content in their blood is still detectable after surgery.

Following a thyroglobulin test, a medical professional could recommend radioactive iodine scans and/or treatments to find and/or eliminate any thyroid cancer or normal thyroid tissue that may still be present. Thyroglobulin levels are then rechecked a few weeks or months later to make sure the treatment was effective, and they are then routinely tested after that.

The cancer is likely returning or spreading if the level of thyroglobulin is low for a few weeks or months following surgery but gradually starts to climb over time.

Thyroglobulin levels that are declining in Graves disease patients after treatment show a positive response.

The test is not frequently requested with illnesses like goiter, thyroiditis, or hyperthyroidism, but people with these conditions may have elevated thyroglobulin levels.

Most Common Questions About the Quantitative Thyroglobulin without TGAB test:

Test Purpose and Indications

Why is the Quantitative Thyroglobulin without TGAB test ordered?

The Quantitative Thyroglobulin without TGAB test is primarily ordered to monitor patients with differentiated thyroid cancer after they have undergone thyroidectomy. It assesses the effectiveness of the surgery and can detect recurrent or metastatic cancer.

How does the Quantitative Thyroglobulin without TGAB test differ from a standard thyroglobulin test?

The Quantitative Thyroglobulin without TGAB test specifically measures thyroglobulin levels without considering the thyroglobulin antibodies (TGAB). This is important because TGAB can interfere with the thyroglobulin measurement, leading to inaccurate results.

Test Interpretation

What does a detectable thyroglobulin level mean after thyroidectomy?

A detectable thyroglobulin level after thyroidectomy, especially when combined with other diagnostic tests, can be indicative of remaining thyroid tissue or recurrent/metastatic differentiated thyroid cancer.

If the Quantitative Thyroglobulin without TGAB test shows undetectable levels, is it a guarantee that the cancer will not recur?

While an undetectable thyroglobulin level is a positive sign and suggests that the surgery was effective, it does not guarantee that the cancer won't recur. Regular monitoring and follow-up tests are essential to catch any potential recurrences early.

General Information

How is the sample for the Quantitative Thyroglobulin without TGAB test collected?

The sample for the Quantitative Thyroglobulin without TGAB test is typically drawn from a vein in the arm using standard venipuncture procedures.

Do other conditions affect the results of the Quantitative Thyroglobulin without TGAB test?

Yes, conditions like thyroiditis or benign thyroid diseases can cause elevated thyroglobulin levels. This is why it's crucial to interpret the test results in the context of the patient's clinical history and other diagnostic results.

Test Accuracy and Reliability

Can biotin supplements interfere with the Quantitative Thyroglobulin without TGAB test?

Yes, biotin can interfere with many lab tests, including the Quantitative Thyroglobulin without TGAB test. If a patient is taking biotin or biotin-containing supplements, they should inform their healthcare provider.

How frequently should the Quantitative Thyroglobulin without TGAB test be performed post-thyroidectomy?

The frequency of testing varies depending on the individual's risk category and the results of the initial post-operative test. In general, the test may be done a few weeks after surgery and then periodically thereafter. The specific timeline should be determined by the treating physician based on the patient's individual circumstances.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Thyroglobulin

The thyroglobulin test is primarily used as a tumor marker to evaluate the effectiveness of treatment for thyroid cancer and to monitor for recurrence. Not every thyroid cancer will produce thyroglobulin, but the most common types, the well-differentiated papillary and follicular thyroid cancers, frequently do, resulting in increased levels of thyroglobulin in the blood.
*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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