Antithyroid peroxidase autoantibodies in thyroid diseases

Area of Science:

• Endocrinology
• Immunology
• Clinical Diagnostics

Background:

• Thyroid microsomal antibodies (anti-M Ab) are now understood to target thyroid peroxidase (TPO).
• While methods to detect anti-TPO antibodies (anti-TPO Ab) exist, clinical data on their usefulness is limited.
• A new monoclonal antibody-assisted radioimmunoassay (RIA) for anti-TPO Ab has been developed.

Purpose of the Study:

• To evaluate the clinical usefulness of a new monoclonal antibody-assisted RIA for detecting anti-TPO Ab.
• To compare the sensitivity and specificity of this new assay with traditional anti-M Ab testing.
• To assess the prevalence of anti-TPO Ab in various thyroid conditions.

Main Methods:

• Assayed anti-TPO Ab using a monoclonal antibody-assisted RIA in 715 subjects (119 controls, 596 patients).
• Compared RIA results with traditional anti-M Ab titers (passive hemagglutination) where available.
• Conducted absorption studies to investigate interference from anti-thyroglobulin antibodies (anti-Tg Ab).

Main Results:

• Anti-TPO Ab were detected in 8.4% of controls and significantly higher in patients with Graves' disease (74%), Hashimoto's thyroiditis (99.3%), and idiopathic myxedema (99.3%).
• The new anti-TPO Ab RIA demonstrated higher sensitivity and specificity compared to anti-M Ab by passive hemagglutination.
• Absorption studies confirmed that anti-Tg Ab can interfere with anti-M Ab tests, but not with the anti-TPO Ab RIA.

Conclusions:

• Monoclonal antibody-assisted RIA for anti-TPO Ab is more sensitive and specific for autoimmune thyroid diseases than anti-M Ab determination by passive hemagglutination.
• The assay is easy to perform and uses minimal purified antigen, suggesting suitability for clinical routine.
• This improved diagnostic method aids in the accurate identification of autoimmune thyroid conditions.