Frequency and characteristics of antibody negative chronic thyroiditis: an experience from a tertiary center

Abstract

Objective: Limited literature is relevant to antibody-negative chronic thyroiditis (AN-CT).The aim was to investigate the frequency and characteristics of AN-CT and explore the presence of other autoimmune and autoinflammatory diseases in patients with AN-CT. Methods: Consecutive participants in the follow-up above 18 years old diagnosed with hypothyroidism caused by chronic thyroiditis (CT) between December 2016 and March 2024 were included in the study. A total of 767 euthyroid patients with CT under levothyroxine (LT4) treatment were analyzed retrospectively. The patient group was divided into 2 subgroups: antibody-negative and antibody-positive. Characteristics and comorbid conditions were compared between the 2 groups. Results: There were 582 patients (75.9%) with classic Hashimoto's thyroiditis (antibody-positive) and 185 patients (24.1%) with AN-CT in the study group.The female/male ratio was similar in the 2 groups (P = .730).The median body mass index was comparable between the 2 groups (P = .486). Median age (P = .003) and thyroid nodule frequency (P = .011) were significantly higher in the AN-CT group. The duration of hypothyroidism was shorter (P = .022), and the daily LT4 dose to achieve euthyroidism was lower (P < .001) in patients with AN-CT. The presence of other autoimmune and autoinflammatory diseases did not differ between the 2 groups. Conclusion: In this study group, AN-CT frequency was 24.1%. Older age, shorter duration of hypothyroidism, higher thyroid nodule frequency, and lower daily LT4 dose to achieve euthyroidism were associated with AN-CT. However, patients with AN-CT had similar behavior relevant to other autoimmune and autoinflammatory disorders when compared with Hashimoto's patients.