Thyroid gland disorders

• The thyroid gland produces all of the T4 and 20% of T3. • Congenital hypothyroidism is caused by: ◦ anatomical defects: agenesis/dysgenesis, ectopic, sublingual ◦ inborn errors of thyroid hormone metabolism ◦ secondary (pituitary thyroid-stimulating hormone (TSH)) or tertiary (hypothalamic thyrotropin-releasing hormone) deficiency ◦ iodine deficiency (commonest cause worldwide of hypothyroidism, patients are usually euthyroid). • Genetic causes are rare. • In most countries worldwide, newborn TSH screening is performed at 0–5 days of age. Treatment with l-thyroxine is (usually) lifelong. • Neonatal thyrotoxicosis due to transplacental passage of thyroid-stimulating immunoglobulins (TSIs) from mothers with thyrotoxicosis/Graves’ disease and may require antithyroid drugs (ATDs). • Acquired autoimmune hypothyroidism in children and adolescents: ◦ is caused by lymphocytic infiltration of the thyroid gland (Hashimoto’s disease/thyroiditis) • raised thyroid peroxidase antibodies are diagnostic • treatment is with l-thyroxine. • Hyperthyroidism (Graves’ disease, Hashimoto’s stimulatory phase (Hashitoxicosis)): ◦ is caused by autoantibodies to the TSH receptor (TSI, or TRAbthyrotropin receptor antibody) ◦ the first-line drug of choice is the ATD carbimazole ◦ thyroidectomy or radioiodine treatment can be considered for drug-resistant cases or after relapse. • Thyroid cancer is rare in childhood and adolescence, usually presenting with a nodule, but can be part of the multiple endocrine neoplasia syndromes.