The clinical characteristics and treatment response of myasthenia gravis with positive thyroid peroxidase antibody or thyroid globulin antibody.

BACKGROUND AND PURPOSE: Myasthenia gravis (MG) frequently associates with thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb), indicating shared autoimmunity. This study investigated the impact of TPOAb/TgAb on MG severity and pathogenesis, to inform improved management.

METHODS

We retrospectively analyzed 144 MG patients (Jan 2022-Dec 2024), stratified into four groups by TPOAb/TgAb status. We compared demographic and clinical profiles, analyzed the effects of disease duration, stage, and onset age on TPOAb/TgAb titers, and evaluated treatment responses across groups.

RESULTS

Among 144 included patients, 55.6 % were thyroid antibody (TAb) - positive (TPOAb + TgAb-: 18.8 %; TgAb + TPOAb-: 9.7 %; TPOAb + TgAb+: 27.1 %). Median onset age was 61 years, 67.5 % were female. TPOAb + TgAb- MG primarily presented as MGFA I (70.4 %), initial onset (63.0 %), with low thymoma (3.7 %) and no TitinAb/RyRAb. TPOAb + TgAb + MG exhibited a severe phenotype: higher MGFA III (30.8 %), relapsed (71.8 % vs 50.0 % in TPOAb-TgAb-, P = 0.030), thymoma (43.6 %), and TitinAb/RyRAb positivity (43.6 %/25.6 %). TgAb titers were significantly higher in relapsed MG (P = 0.001). Both TPOAb + TgAb+ and TPOAb-TgAb- MG responded better to pyridostigmine 90 mg/day, TPOAb + TgAb + MG showed superior response to high-dose glucocorticoids (40-60 mg/day) compared to TPOAb-TgAb- (P = 0.006). However, multivariate analysis indicated TPOAb + TgAb + status itself was not an independent predictor (OR = 0.077, 95 % CI: 0.000-23.487; P = 0.380).

CONCLUSIONS

This study demonstrates the clinical significance of TPOAb/TgAb in MG. TPOAb + TgAb + status identifies a clinical subgroup with a "triple-high" profile. TgAb may show potential as a disease activity biomarker. These findings inform precision treatment strategies, pending validation in large prospective studies.