[Prevalence and predictive factors of parietal cell antibody positivity in autoimmune thyroid disease]

Our aim was to evaluate the prevalence of parietal cell antibodies (PCA) in patients with autoimmune thyroid disease (ATD).

We performed a descriptive, cross-sectional study of patients with ATD. The presence of PCA was determined. Elevated antithyroid antibodies (ATAs) were defined as those higher than the 75th percentile of distribution. Multivariate logistic regression models were built to assess the independent contribution of the following variables to PCA positivity: age, sex, hemoglobin, medium corpuscular volume (MCV), dose/Kg of levothyroxine (LT4), disease duration and elevated ATA levels.

A total of 148 patients were included (137 females). The mean age was 45.7 (SD 15) years and disease duration was 4.5 (SD 4) years. Forty-three patients (29%) with Graves' disease and 105 (71%) with primary hypothyroidism were included. The 75th percentile of distribution was 420U/ml for anti-peroxidase antibodies and 200U/ml for anti-thyroglobulin antibodies. PCA positivity was found in 30 patients, with an overall prevalence of 20.3%. PCA positivity with titers higher than 1/640 was found in 19 patients (12.8%). The only independent predictive factor of PCA positivity was the presence of elevated levels of ATAs (odds ratio (OR)=3; 95% confidence interval (CI): 1.1-8.6; p=0.04). The only independent predictive factor of PCA positivity at titers >/=1/640 was also the presence of elevated levels of ATAS (OR=7.3; 95% CI: 1.6-32.7; p=0.009).

The prevalence of PCA positivity in patients with ATD was 20%. Elevated levels of ATAs increase the risk of PCA positivity.