Arq Bras Endocrinol Metab 2002;46(2):167-172
Development and Validation of an Immunofluorometric Assay for Serum Thyroid Anti-Peroxydase Antibodies
DOI: 10.1590/S0004-27302002000200009
We developed an assay in which highly purified human TPO is adsorbed to microtiter plate wells; after incubation with the study serum samples, presence of specific antibodies is revealed by a monoclonal europium-labeled antibody against human IgG. The sensitivity of the test is 0.6U/mL, and the reproducibility quite acceptable. We analyzed serum samples from: 188 normal subjects of both sexes, 74 of whom >65 years of age; 54 patients with Graves’ disease (GD) and 13 with Hashimoto thyroiditis (HT). Based on 97 routine samples, the method was compared to a commercial RIA, and a high concordance was found, with a kappa index of 0.959. The definition of a cut-off value for the presence of anti-TPO antibodies was based on a ROC curve and was set at 10U/mL. Positive anti-TPO values were found in 9.6% of the normal subjects up to 64 years of age, and in 16.5% of those >65 years. Patients with GD presented 85.2% of positivity, and those with HT showed 100% positivity. Thus, we described a sensitive and specific easy to perform assay, for detection of autoantibodies against thyroid peroxidase in patients with thyroid autoimmune diseases.