Case presentation:
A 34-year-old woman presented to our department with acute seronegative polyarthritis.
She had high thyroid-stimulating hormone levels, low thyroxine levels, and positive thyroid peroxidase antibodies. Ultrasonography revealed a thyroiditis aspect.
The diagnosis of Hashimoto’s thyroiditis was made.
There were no clinical nor immunological features for the diagnosis of Sjögren’s syndrome, rheumatoid arthritis, systemic lupus erythematosus.
After three months of thyroid hormone replacement therapy, the thyroid-stimulating hormone level had become within the normal range, and polyarthritis had resolved.