Hashimoto's Thyroiditis in Noonan Syndrome: A Case Report

Noonan syndrome is a genetic, developmental disorder characterized by facial deformities, congenital heart defects, webbed neck, wide space nipples, and growth hormone deficiencies. We report a case of a 15-year-old female patient who presented to the outpatient department with recurrent puffiness of both eyes, easy fatiguability, and dyspnea on exertion. The condition was associated with bilateral proximal muscular weakness of lower limbs with positive Gower's sign. On examination, the patient had a webbed neck, hypertelorism, a shielded chest, short stature, and a high-arched palate. Thyroid function tests revealed hypothyroidism. Chromosomal analysis revealed 46 XX. After excluding Turner syndrome on karyotyping, Noonan syndrome with hypothyroidism was diagnosed. The patient was started on levothyroxine and referred to a pediatric endocrinologist for further growth and development assessment. Autoimmune hypothyroidism in a patient with Noonan Syndrome is rare; it may occur as a separate entity or have some genetic susceptibility. Further research is needed to determine the association of autoimmune hypothyroidism with Noonan syndrome.