Association of Anti-TPO and Anti-TG Antibody Levels with Cytological Categorisation of Thyroiditis

Abstract

Background: Thyroiditis represents a heterogeneous group of inflammatory thyroid disorders with overlapping clinical, biochemical, and cytomorphological features. Autoimmune thyroiditis, particularly Hashimoto’s thyroiditis, is commonly associated with circulating antithyroid antibodies, notably anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies. Fine-needle aspiration cytology (FNAC) remains the diagnostic cornerstone for thyroiditis, especially in cases with equivocal clinical or serological findings.

Objectives: To evaluate the association between anti-TPO and anti-TG antibody levels and cytological categorisation of thyroiditis and to correlate cytomorphological patterns with clinical and biochemical parameters.

Methods: This hospital-based prospective observational study included 150 cytologically proven cases of thyroiditis evaluated at Patna Medical College and Hospital over a two-year period. Clinical features, thyroid function tests, antithyroid antibody levels, and FNAC findings were analysed and correlated.

Results: Hashimoto’s thyroiditis constituted the predominant cytological diagnosis (82%), followed by De Quervain’s thyroiditis (18%). Elevated anti-TPO and anti-TG antibody levels were significantly associated with cytological features of Hashimoto’s thyroiditis, including lymphocytic infiltration, Hurthle cell change, plasma cells, and follicular cell anisonucleosis. Granuloma formation was strongly associated with De Quervain’s thyroiditis. Subclinical hypothyroidism was identified in 40.7% of cases.

Conclusion: Anti-TPO and anti-TG antibodies show a strong association with cytological patterns of autoimmune thyroiditis. FNAC remains the gold standard for accurate categorisation of thyroiditis, particularly in seronegative or early disease. A multidisciplinary diagnostic approach enhances diagnostic accuracy and clinical management.