Autoimmune Thyroiditis Shifting from Hashimoto's Thyroiditis to Graves' Disease.

Area of Science:

• Endocrinology
• Immunology
• Internal Medicine

Background:

• Graves' disease (GD) typically shifts to Hashimoto's thyroiditis (HT), but the reverse is uncommon.
• This report details a rare case of a patient whose HT converted to GD, alongside a review of existing literature.

Approach:

• A 50-year-old woman initially diagnosed with Hashimoto's thyroiditis presented with myxedema and positive thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb).
• Despite thyroid hormone replacement therapy, she developed hyperthyroidism, leading to a diagnosis of Graves' disease.
• Treatment with antithyroid agents successfully managed the hyperthyroidism.

Key Points:

• Only 50 cases of HT converting to GD have been documented, with a median patient age of 44 years and a median conversion time of 7 years.
• The male-to-female ratio in HT-to-GD conversion (1:9) resembles that of GD (1:10) more than general HT (1:18).
• All reported patients with HT converting to GD were on thyroid hormone replacement therapy for hypothyroidism.

Conclusions:

• Continuous monitoring of thyroid stimulating antibodies (TSAb) in patients with HT, especially those who are TSAb-positive or on replacement therapy, is crucial for predicting conversion to GD.
• Understanding the clinical characteristics of patients with preceding HT is vital for accurate diagnosis and management of subsequent GD, minimizing adverse events.