Congenital hypothyroidism and neonatal screening

impact of early diagnosis on child development

Abstract

Introduction: Congenital hypothyroidism (CH) is one of the most common endocrine disorders in the neonatal period and remains one of the leading preventable causes of intellectual disability in children. Objective: To describe a clinical case of CH diagnosed early through newborn screening, emphasizing the impact of early diagnosis and timely therapeutic intervention on child development. Methods: This was a retrospective, descriptive, observational case report based on a review of the electronic medical records of a patient treated at a hospital in the state of Goiás, Brazil. Results: A term female newborn (39 weeks and 5 days of gestation; birth weight, 2,300 g) was admitted to the Neonatal Intensive Care Unit because of respiratory distress following cesarean delivery for acute fetal distress. Newborn screening revealed markedly elevated thyroid-stimulating hormone (TSH) levels (212.74 μIU/mL), subsequently confirmed by serum TSH >100 μIU/mL, triiodothyronine (T3) of 0.58, and free thyroxine (FT4) of 0.72, consistent with primary CH. Echocardiography demonstrated a patent ductus arteriosus (0.32 cm) and patent foramen ovale, with no abnormalities on transfontanellar ultrasonography and antithyroglobulin antibody levels <3.0. Following early initiation of levothyroxine replacement therapy, the patient showed favorable clinical evolution, with resolution of neonatal complications and subsequent transfer to the pediatric ward. Conclusions: The absence of specific clinical manifestations during the first days of life may hinder the early recognition of CH. Newborn screening plays a central role in identifying thyroid dysfunction before the onset of clinical manifestations, enabling diagnostic confirmation and timely initiation of hormone replacement therapy. Early levothyroxine treatment substantially improves the prognosis of the disease.