Thyroid dysfunction in Down's syndrome and screening for hypothyroidism in children and adolescents using capillary TSH measurement

Thyroid dysfunction is more common in individuals with Down's syndrome (DS) than in the general population, whose clinical features can mask the presenting signs and symptoms of hypothyroidism. Biochemical screening is necessary; however, venepuncture may be difficult. Aims: To assess the prevalence of thyroid dysfunction in children and adolescents with DS and the feasibility of screening for hypothyroidism using capillary dried blood spot thyroid stimulating hormone (TSH) from infancy. Methods: 394 children (217 boys, 177 girls) were clinically assessed for thyroid dysfunction and 305 children (aged 4 months to 18.9 years) were screened for hypothyroidism by capillary whole blood TSH sample. Results: Thyroid dysfunction was detected in 4.6%, with 50% unscreened since neonatal screening. Parents reported minimal distress by fingerprick screening. Conclusion: DS is associated with an increased prevalence of thyroid. dysfunction, particularly in preschool children. Biochemical screening is essential and capillary whole blood TSH sampling for hypothyroidism is feasible, less invasive and acceptable.