A Homoclinic Orbit in a Patient-Specific Model of Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis is an autoimmune disorder of the thyroid gland. In Hashimoto disease, the immune system damages the follicular cells of the thyroid gland through humoral and cellular-mediated responses which result in diminishing production of thyroid hormones in the blood over time. Using a patient-specific model of Hashimoto’s thyroiditis, we describe the natural history of Hashitoxicosis in genetically susceptible individuals. Hashitoxicosis means a sudden leakage of thyroid hormones from the gland. The main result of this present work is to show the existence of a homoclinic orbit which forms the boundary for the asymptotically stable interior diseased steady state. This homoclinic orbit corresponds to the clinical condition of Hashitoxicosis.