Prevalence of anti-gastric parietal cell antibodies in anti-TPO positive patients with Hashimoto thyroiditis and graves’ disease: Insights from a tertiary care centre in Pakistan

Objective: To determine the prevalence of anti-gastric parietal cell (GPC) antibodies in anti-TPO-positive patients with Hashimoto thyroiditis and Graves’ disease. Material and Methods: A cross-sectional descriptive study was conducted at the Immunology Department, Armed Forces Institute of Pathology (National University of Medical Sciences) Rawalpindi, from September 2024 to February 2025. Patients clinically suspected of Hashimoto thyroiditis or Graves’ disease with positive anti-TPO antibodies and informed consent were included. Anti-TPO was detected by ELISA and anti-GPC antibodies by indirect immunofluorescence. Association between antibodies was assessed using Chi-square or Fisher’s exact test; p < 0.05 was considered significant. Results: Out of 200 anti-TPO antibody positive patients tested for anti-GPC antibodies, 26.5% tested positive. Among the 53 (26.5%) positive cases, 37 (18.5%) were females and 16 (8%) were males, with no significant association between gender and anti-GPC status (p = 0.751). The clinical data of 63 (31.5%) patients was available. Among them, 17 (26.9) tested positive for Anti-GPC antibodies, with 12 (19%) having Hashimoto's thyroiditis and 5 (7.9%) having Graves’ disease. No significant correlation was found between Anti-GPC antibodies and the type of autoimmune thyroiditis (p = 0.443). Conclusions: This study identified Anti-GPC antibody positivity in 26.5% of patients with autoimmune thyroiditis, with no significant correlation to gender or thyroiditis subtype. These findings highlight the potential value of routine Anti-GPC antibody screening and highlight the need for long-term studies to better understand their clinical significance. Keywords: Anti-gastric-parietal cell antibodies, Anti-thyroid peroxidase antibody, Anti-thyroglobulin antibody, Hashimoto’s thyroiditis