Anti-Thyroid Antibodies

What sample is needed for Anti-Thyroid Antibody?

1. The serum is needed.
2. The fasting sample is preferred.
3. Stop vitamins before taking the sample.

What are the thyroid autoantibodies?

1. The auto-antibodies are directed against various self-antigens like cellular components (Antimicrosomal antibodies) or proteins(thyroglobulins).
2. These autoantibodies are found in the autoimmune diseases of the thyroid gland.

What are the thyroid autoantigens?

1. Thyroglobulin.
2. Thyroid microsomal antigen (the vesicle-like structure formed from the endoplasmic reticulum when cells are disrupted).
3. Thyroperoxidase (a component of thyroid microsomal antigen).
4. TSH-Receptor (Thyrotropin receptor).
5. Rarely are auto-antigens against:
   1. TSH.
   2. T4 and T3

What are the thyroid auto-antibodies?

1. Antithyroglobulin antibody.
2. Antimicrosomal antibody.
3. Anti-thyroid peroxidase antibody.
4. Long-acting thyroid-stimulating antibody (LATS) includes:
   1. TSI = thyroid-stimulating immunoglobulin.
   2. TSH-R antibody = thyroid hormone receptor antibody.

Antithyroid microsomal antibody: 

What is the importance of antithyroid microsomal antibody?

1. The microsomal antibody is the older name, and now it is correctly called antithyroid peroxidase antibodies.
2. These are called microsomal because thyroid peroxidase is an enzyme in the microsomes of thyroid follicular cells.
3. This test differentiates between Hashimoto’s thyroiditis and chronic lymphocytic thyroiditis in children.
   1. These are found more in chronic thyroiditis than antithyroglobulin antibodies.
4. These are present in 70% to 90% of Hashimoto’s thyroiditis.
5. This antibody is against the microsomes of the thyroid cells.
6. There is a cytotoxic injury to the thyroid follicles.

What are the methods to detect thyroid microsomal antibody?

Thyroid microsomal antibodies can be detected by:

1. Complement fixation test.
2. Immunofluorescence of tissue biopsy.
3. Passive hemagglutination.
4. ELISA method.
5. Radioimmunoassay (RIA).

What are the normal Antimicrosomal antibodies?

1. Negative = < 1:100
2. 5% to 10% are present in healthy people without thyroid disease.

Antithyroid peroxidase antibody:

What is the significance of antithyroid peroxidase antibody?

1. Anti-thyroid peroxidase autoantibodies are replacing atimicrosomal antibodies and anti-thyroglobulins.
2. This is recognized as the thyroid microsomes’ principal and possibly only autoantigen component.
3. This is suggested as a routine in the case of thyroid autoimmune disease.
4. The thyroid microsomal antibodies are difficult to detect.
5. There are irrelevant thyroid antigens, autoantibodies, and contamination of microsomes with thyroglobulin.
6. The thyroperoxidase antibody eliminates these complications.
7. The RIA and chemiluminescence can detect these antibodies.
   1. The above two methods are more accurate than passive hemagglutination.
8. Antiperoxidase antibodies are seen in the following:
   1. These are seen in Hashimoto’s thyroiditis, idiopathic myxedema, and most cases.
   2. These are positive in 90% of the cases of Hashimoto’s thyroiditis.
   3. The high titer of these antibodies suggests Hashimoto’s thyroiditis, but its negative value does not rule out Hashimoto’s thyroiditis.
9. Anti-thyroid peroxidase antibody is seen in the following:
   1. A titer of >1:1,000 is seen in Graves’ disease and Hashimoto’s thyroiditis.
   2. Grave’s disease.
   3. Diabetes mellitus type 1.
   4. It may be seen in nonimmune thyroid disease.
10. What is the normal anti-thyroid peroxidase antibody?
    1. Titer = <1:100

Thyrotropin receptor antibody (TSH-R antibody):

What is the significance of thyrotropin receptor antibody (TSH-R antibody)?

1. Some immunoglobulins bind to the thyroid cell membrane near or to the TSH-receptor site.
2. These are often seen in the blood of Graves’ disease patients.
3. These are also found in other thyroid autoimmune diseases.
4. What are the functions of the TSH-R antibody?
   1. In some cases, they may have a stimulatory effect.
   2. In some cases, they block the TSH-receptor site and decrease thyroid function.
   3. In some, there may be no effect.
   4. Their functional role may be in the pathogenesis of Graves’ disease.
   5. It is found as a long-acting thyroid stimulator in these patients’ serum.

What are the causes of an Antithyroid antibody-positive test?

1. Chronic thyroiditis (40% to 70 %).
2. Thyrotoxicosis (Graves’ disease).
3. Hypothyroidism.
4. Hashimoto’s thyroiditis.
5. Pernicious anemia.
6. Other autoimmune diseases include rheumatoid arthritis and systemic lupus erythematosus.

What are the various auto-antibodies and thyroid diseases?

• LATS antibodies are of two types:
  • TSI = Thyroid-stimulating immunoglobulin.
  • TSH-R antibody = Thyroid-stimulating hormone receptor antibody.
• Please see more details on the Antithyroglobulin antibody.+

What are the causes of Antimicrosomal autoantibodies?

1. Hashimoto’s thyroiditis.
2. Thyroid cancer.
3. Myxedema.
4. Sjögren’s syndrome.
5. Goiter.
6. Autoimmune hemolytic anemia.
7. Lupus erythematosus.

What are the conditions for antimicrosomal antibody/antithyroglobulin Ab positivity?

• Either hemagglutination or immunofluorescent methodology can do the above tests.

How will you summarize thyroid autoantibodies?

1. Anti-thyroglobulin antibody:

1. These antibodies are a sign of Hashimoto’s thyroiditis.
2. There is a high level of these antibodies.
3. These are positive in Graves’ disease.
4. Positive in follicular and papillary carcinoma.
5. Other autoimmune disorders:
   1. Type 1 diabetes mellitus.
   2. Pernicious anemia.
   3. Rheumatoid arthritis.
   4. Systemic lupus erythematosus (SLE).

2. Thyroid peroxidase antibody:

1. These antibodies are a sign of Hashimoto’s thyroiditis.
   1. 90% of the patients are positive for Hashimoto’s thyroiditis.
2. These are autoimmune antibodies that lead to hypothyroidism.
3. Graves’ disease is hyperthyroidism.
   1. It is positive in 70% to 80% of Graves’ disease.

3. Thyroid microsomal antibodies:

1. These antibodies are present in Hashimoto’s thyroiditis.
2. It differentiates Hashimoto’s thyroiditis from chronic lymphocytic thyroiditis.

4. Thyroid-stimulating hormone (TSH) receptor:

1. These antibodies are signs of Graves’ disease.
   1. 90% of the Graves’ disease patients have positive results for this antibody.
   2. It can be done to follow up on Graves’ disease.

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