What is the Difference TRAb and TSI Test

Your body has its own defense system, equipped with antibodies designed to protect you from harmful invaders. But what happens when these antibodies turn against your own cells? Welcome to the world of autoantibodies, where the immune system mistakenly targets self-antigens. To detect these renegade antibodies, medical professionals turn to specialized tests. Among them are the TRAb and TSI tests, essential tools in diagnosing autoimmune thyroid disorders. These tests delve deep into the bloodstream, uncovering clues about thyroid receptor antibodies – the culprits behind certain thyroid malfunctions.

The key difference between TRAb and TSI Test is their function. The TRAb test measures all three types of TRAb in the blood, while the TSI test measures the net stimulatory activity of all TRAb in the blood.

CONTENTS

1. Overview and Key Difference
2. What is TRAb Test  
3. What is TSI Test
4. Similarities – TRAb and TSI Test
5. TRAb vs TSI Test in Tabular Form
6. Summary – TRAb vs TSI Test
7. FAQ – TRAb and TSI Test

What is TRAb Test?

TRAb test is used to measure all three types of TRAb (stimulating, blocking, and neutral antibodies) in the blood. Healthcare providers may recommend a TRAb test for individuals exhibiting symptoms consistent with hyperthyroidism (an overactive thyroid gland) or Graves’ disease.

However, it’s important to note that these autoantibodies are only present in approximately 90% of people with Graves’ disease. Therefore, a negative test result doesn’t definitively rule out the disease. This limitation underscores the importance of considering clinical symptoms alongside test results for accurate diagnosis.

Additionally, there are potential risks associated with the TRAb test, including a small red mark at the needle insertion site, bruising, and the rare possibility of infection. These risks should be discussed with the healthcare provider prior to undergoing the test.

What is TSI Test?

The TSI test is used to measure the net stimulatory activity of all TRAb in the blood. Essentially, it quantifies the level of thyroid-stimulating immunoglobulins present. These immunoglobulins typically instruct the thyroid gland to increase activity, releasing excessive thyroid hormone into the bloodstream. The TSI test is used for detecting conditions such as Graves’ disease, toxic multinodular goiter, and thyroiditis.

However, it’s important to acknowledge potential risks associated with this test, including excessive bleeding, fainting or lightheadedness, multiple punctures, hematoma formation, and the risk of infection. Before the test, these risks should be considered and discussed with the healthcare provider.

Similarities Between TRAb and TSI Test

1. TRAb and TSI tests are two types of tests used to diagnose autoantibodies in the blood.
2. They are blood tests.
3. Both can be used to detect Graves’ disease.
4. Both have risks and limitations.

Difference Between TRAb and TSI Test

Definition

1. TRAb test is used to measure all three types of TRAb (stimulating, blocking, and neutral antibodies) in the blood.
2. TSI test measures the amount of thyroid-stimulating immunoglobulins in the blood.

Diseases Detected

1. TRAb test is used to detect hyperthyroidism or Graves’ disease.
2. The TSI test is used to detect Graves’ disease, toxic multinodular goiter, and thyroiditis.

Risks

1. Risks associated with the TRAb test include a small red mark where the needle is inserted, an area of bruise, and potential infections.
2. On the other hand, risks associated with the TSI test include excessive bleeding, fainting or feeling lightheaded, multiple punctures, hematoma, and infection.

The infographic below presents the differences between TRAb and TSI Test in tabular form for side-by-side comparison.

Summary – TRAb vs TSI Test

TRAb test measures all three types of TRAb in the blood. However, the TSI test measures the net stimulatory activity of all TRAb in the blood. Moreover, TRAb is used to diagnose hyperthyroidism or Graves’ disease, whereas the TSI test is used to diagnose Graves’s disease, toxic multinodular goiter, and thyroiditis. Thus, this summarizes the difference between TRAb and TSI Test.

FAQ: TRAb and TSI Test

1. Are TRAb and TSI the same?

TRAb and TSI are not the same. In these tests, the antibody measured is known as TSH receptor antibody (TRAb), which are of three types: stimulating, blocking, and neutral antibodies. There are two methods of measuring the TRAb: the thyroid-stimulating immunoglobulin (TSI) assay and the TSH receptor-binding inhibitor immunoglobulin (TBII or TRAb) assay.

2. What is the other name for the TRAb test?

Other names for the TRAb test are TBII, anti-thyrotropin, anti-TSHR, antibodies to TSH receptor.

3. What is the role of TRAb test?

• The performance of TRAb in the differential diagnosis of hyperthyroidism and Graves’ disease is excellent, with sensitivity and specificity in the upper 90%. TRAb can accurately predict short-term relapses of hyperthyroidism after a course of antithyroid drugs. However, they are less effective in predicting long-term relapses or remissions.

4. What are the different types of TRAb?

• Functionally, TRAb can be divided into three categories: 1) thyroid stimulating antibodies (TSAb; TSI and 2), thyroid blocking antibodies (TBAb, TBI) and neutral antibodies.

5. What is TSI antibody test?

• TSIs (thyroid stimulatory antibodies) are antibodies that tell the thyroid gland to become more active and release excess amounts of thyroid hormone into the blood. A TSI test measures the amount of these thyroid stimulating immunoglobulin in the blood.

Reference:

1. “TSH Receptor Antibody (Trab) Test: Purpose, Procedure, Cost & Result …” Metro Polis India.
2. Holm, Gretchen. “TSI Level Test: Purpose, Procedure, and Results.” Healthline, Healthline Media.

Image Courtesy:

1. “HIV Antibody Testing Kit” By NIAID (CC BY 2.0 DEED) via Flickr