Anti-Thyroid Microsomal Antibody, Anti-Thyroid Peroxidase antibody, Thyrotropin-Receptor Antibody
- The serum is needed.
- The fasting sample is preferred.
- Stop vitamins.
- These may be any number of antibodies directed against various self-antigens like cellular components (Antimicrosomal antibodies), or proteins( thyroglobulins).
- These autoantibodies are found in the autoimmune diseases of the thyroid gland.
- There are four autoantigens:
- Thyroid microsomal antigen (the vesicle-like structure formed from the endoplasmic reticulum when cells are disrupted).
- TSH-Receptor (Thyrotropin receptor).
- Thyroperoxidase (a component of thyroid microsomal antigen).
- The antibodies are:
- Antithyroglobulin antibody.
- Antimicrosomal antibody.
- Long-acting thyroid-stimulating antibody (LATS), it includes:
- TSI = thyroid-stimulating immunoglobulin.
- TSH-R antibody = thyroid hormone receptor-antibody.
- Antithyroid microsomal antibody:
- This test differentiates between Hashimoto’s thyroiditis and chronic lymphocytic thyroiditis in children.
- These are present in 70 to 90% of Hashimoto’s thyroiditis.
- This antibody is against the microsomes of the thyroid cells.
- There is a cytotoxic injury to the thyroid follicles.
- Antithyroid peroxidase antibody:
- This is recognized as the principal and possibly only autoantigen component of the thyroid microsomes.
- This is suggested in routine the case of autoimmune disease of the thyroid.
- The thyroid microsomal antibodies are difficult to perform and a limited amount of human thyroid tissue.
- There are irrelevant thyroid antigens and autoantibodies, and contamination of microsomes with the thyroglobulin.
- These complications are eliminated by the thyroperoxidase antibody.
- These antibodies can be detected by the RIA and chemiluminescence.
- The above two methods are more accurate than passive hemagglutination.
- Antiperoxidase antibodies are seen in:
- These are seen in the Hashimoto’s thyroiditis, and idiopathic myxedema, and the majority of
- Grave’s disease.
- Diabetes mellitus type 1.
- May be seen in the nonimmune thyroid disease.
- Thyrotropin receptor antibody (TSH-R antibody):
- There are immunoglobins that bind to the thyroid cell membrane near or to the TSH-receptor site.
- These are often seen in Grave’s disease patient’s blood.
- These are also found in other thyroid autoimmune diseases.
- Their function is variable:
- In some cases, they may have a stimulatory effect.
- In some cases, they block the TSH-receptor site and decrease the thyroid function.
- In some, there may be no effect.
- Their functional role may be in the pathogenesis of Grave’s disease when long-acting thyroid stimulator was found in the serum of these patients.
A lab diagnosis method for thyroid microsomal antibody:
Thyroid microsomal antibody can be detected by:
- Complement fixation test.
- Immunofluorescence of tissue biopsy.
- Passive hemagglutination.
- ELISA method.
- Radioimmunoassay (RIA).
- Negative = < 1:100
Antithyroid Ab Positive in:
- Chronic thyroiditis (40 to 70 %).
- Thyrotoxicosis (Grave’s disease).
- Hashimoto’s thyroiditis.
- Pernicious anemia.
- Other autoimmune diseases like Rheumatoid arthritis, and systemic lupus erythematosus.
- Table showing various thyroid diseases and auto-antibodies
|Disease||Anti-thyroglobulin antibody||Anti-microsomal antibody||
stimulating antibody (LATS)
|Grave’s disease||positive 30%||positive 60 to 80%||positive >85%||positive 100%|
|Hashimoto’s thyroiditis||positive 70 to 90%||positive 80%||positive 100%||negative|
|Lymphocytic thyroiditis||positive 30 to 50%||positive 50%||positive||negative|
|Thyroid carcinoma||positive 20 to 50%||positive 15%||negative|
|Normal person||positive low titer||positive low titer, 5 to 10%||positive 5 to 10%|
- 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.