Hashimoto’s Thyroiditis: Causes, Symptoms, and Treatments December 15, 2023December 6, 2022 by Team Wakeup For Health In Hashimoto’s disease, your immune system attacks your thyroid. Hashimoto’s disease causes swelling of the thyroid. This is called ‘chronic lymphocytic thyroiditis’ in medical language. This disease is the main cause of hypothyroidism.