Snapshot A six-week-old male presents with lethargy and hypotonia. On physical exam, he is jaundiced and has a large protruding tongue. Introduction Insufficient iodine intake or defect in T4/thyroid formation leading to fetal hypothyroidism T4 is crucial during first two years of life for normal brain development Cretinism refers to login to view 2 more bullets Presentation Symptoms login to view 5 more bullets Evaluation Labs login to view 2 more bullets Treatment Treat with levothyroxine replacement Prognosis, Prevention, and Complications Prevention by newborn screening by law