Hypothyroidism (Pediatric)

Definition

Hypothyroidism in children is a condition characterized by insufficient production of thyroid hormones, leading to growth retardation, developmental delay, and multiple systemic effects.

Epidemiology

• Congenital hypothyroidism occurs in approximately 1 in 2,000–4,000 newborns
• Acquired hypothyroidism is more common in school-aged children and adolescents
• Females are more frequently affected than males in acquired cases
• Autoimmune thyroiditis (Hashimoto’s) is the most common cause in older children
• Early diagnosis through newborn screening significantly improves outcomes

Etiology

• Congenital hypothyroidism: thyroid agenesis, dysgenesis, dyshormonogenesis
• Autoimmune thyroiditis (Hashimoto’s disease)
• Iodine deficiency or excess
• Medications: antithyroid drugs, lithium
• Hypopituitarism or secondary hypothyroidism
• Genetic syndromes affecting thyroid function (rare)

Pathophysiology

• Low thyroid hormone levels reduce basal metabolic rate
• Impaired growth and skeletal maturation
• Delayed brain development in congenital cases if untreated
• Reduced protein synthesis and metabolic processes
• Accumulation of mucopolysaccharides in tissues leading to puffiness, macroglossia, and edema
• Altered lipid metabolism may lead to hypercholesterolemia
• Cardiovascular and neuromuscular function may be affected