The paper describes the case of a 13-year-old girl with diagnosis of panic attack and treated with antidepressant therapy. She had sudden episodes of air hunger and difficulty in breathing that resolved spontaneously. She had a transient initial benefit after medical therapy, then these attacks recurred. Laboratory blood test showed low TSH, high fT4 and elevated thyroid peroxidase antibody titer. A thyroid ultrasound revealed thyroiditis and an autoimmune thyroiditis in phase of hyperthyroidism (Hashitoxicosis) diagnosis was made. Hashimoto thyroiditis is the most common cause of acquired hypothyroidism in children and adolescents. Children with Hashimoto thyroiditis may present with a euthyroid goiter, subclinical hypothyroidism, profound hypothyroidism with growth retardation and, rarely, hyperthyroidism. Hashitoxicosis (Htx) refers to the presence of biochemical hyperthyroidism in patients with autoimmune thyroiditis. It is important to exclude an organic cause in a patient with psychiatric symptoms especially in adolescence age.