Seropositivity to anti-thyroid peroxidase and anti-thyroglobulin autoantibodies in hypo and hyper-thyroidism: Diagnostic and epidemiological significance

Background: Autoantibodies to thyroid antigens in general, and thyroid peroxidase in particular, are considered as the hallmark of autoimmune thyroid dysfunctions. While a pro-inflammatory response is considered as predominant in hypothyroidism, in Grave’s disease it is a predominant antibody response. Objectives: The objective of the present study was to evaluate seropositivity to TPO and TG antigens in these two conditions with apparently diversified patterns of immune responses. Methods: An Enzyme linked immunosorbent assay was employed for detection of Anti-Thyroid Peroxidase (TPO) and Anti-Thyrooglobulin (TG) auto-antibodies in sera of patients with Hypo and Hyperthyroidism. Results: Total seropositivity to both TPO Ab/ TG Ab was found to be 69.09% in hypo and 66.66% in hyperthyroidism; it was 54.54% and 53.33% for hypo and hyperthyroidism respectively for TPO Ab alone. A substantially less seropositivity of 41.81% and 40% was observed for Hypo and Hyperthyroid respectively for TG Ab. Analysis of seropositivity in relation to age at onset revealed higher sero-posiivity (53.33%) in early onset (≤35 years) group in hypo for TPO Ab. Functional significance of TPO Ab in the two thyroid conditions has been discussed particularly in the light of their diagnostic utility and epidemiological significance. Conclusion: It is concluded that higher sera positivity was observed for TPO compare to TG. These variations may be due to differences in antigenic characteristics of these two thyroid antigens. Keywords: Thyroid dysfunction, Anti-TPO, Anti-TG, Auto-antibodies- Epitopic differences