Hypothyroidism Associated With Different Forms of ANCA-Associated Vasculitis

Hypothyroidism is associated with positive myeloperoxidase (MPO) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and in a subset of patients with granulomatosis with polyangiitis (GPA), according to study results presented at the American College of Rheumatology (ACR) Convergence 2020, held virtually from November 5 to 9, 2020.

Data on thyroid disease were collected from participants with 3 forms of AAV (GPA, n=866; microscopic polyangiitis [MPA; n=167]; and eosinophilic GPA, n=282), all of whom were enrolled in a prospective, multicenter, longitudinal study. The association of thyroid disease with clinical and laboratory variables was assessed with logistic regression.

Thyroid disease was present in 163 (13%) of the 1315 patients with AAV (55% women; mean age at study entry, 52.5±15.8 years); 145 (11%) of these cases were of hypothyroidism and 18 (1.4%) were of hyperthyroidism. It was noted that women were more likely to have thyroid disease (odds ratio [OR], 3.22; 95% CI, 2.19-4.75).

Among patients with GPA, hypothyroidism was associated with MPO-ANCA positivity (OR, 3.01; 95% CI, 1.80-5.02) and perinuclear ANCA (OR 2.32; 95% CI, 1.27-3.94).

On comparing clinical features between patients with and without hypothyroidism, patients with AAV and hypothyroidism were at increased risk for venous thrombosis (14% vs 9%, respectively; OR, 1.84; 95% CI, 1.07-3.14)

“This study confirms an association of hypothyroidism with [perinuclear] ANCA/MPO in patients with AAV,” the study authors concluded. “Further strengthening this observation is the association of thyroid disease with MPO-ANCA in the subset of patients with GPA. Previously hypothesized mechanisms for this finding include homology between thyroid peroxidase antibodies and MPO, or, general loss of tolerance to peroxidases. The increased risk [for] venous thromboembolism in patients with AAV and hypothyroidism warrants further investigation and may be due to additional effects of hypothyroidism on endothelial dysfunction or hypercoagulability.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Kermani T, Cuthbertson D, Carette S, et al. Thyroid disease in patients with ANCA-associated vasculitis. Presented at: ACR Convergence 2020; November 5-9, 2020. Abstract 1432.