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Children and adults with Down’s syndrome are at increased risk of developing thyroid dysfunction, and screening for thyroid dysfunction is recommended as part of their health surveillance.1 Clinical history and examination are known to be unreliable indicators of thyroid dysfunction in Down’s syndrome. Venous blood for thyroid stimulating hormone (TSH) assay remains the gold standard. Capillary blood spot on filter paper TSH has been proposed as a simpler and more convenient alternative screening method for hypothyroidism in these children.2
To establish current screening practices, we under took a postal questionnaire of community paediatricians registered with the British Association for Community Child Health (BACCH). Community paediatricians are the group mostly likely to see children with Down’s syndrome for health surveillance. Paediatricians were asked whether they routinely screened children with Down’s syndrome for thyroid dysfunction. They were asked at what age of child they began screening, how often they screened, and which method they used.
The questionnaire response rate was 64% (209/325). All the paediatricians who returned completed questionnaires routinely looked after children with Down’s syndrome. As expected, almost all of respondents, 93% (194/209), were screening routinely. Most paediatricians began screening before 5 years of age, and screened every two years (table 1). Venous blood TSH was the most frequently used method of screening (83%, 174/209). Only a small number have begun using capillary blood spot on filter paper TSH (7%, 15/209). A few paediatricians were relying on clinical suspicion alone. Those paediatricians not routinely screening for thyroid dysfunction, were either measuring TSH opportunistically or were undertaking biochemical screening only when symptoms or signs raised suspicion.
The Down’s Syndrome Medical Interest Group (DSMIG) has recommended biochemical screening for thyroid dysfunction at least every two years after the first year of life.1 Most paediatricians’ practice is consistent with this recommendation. Capillary blood sampling has practical advantages over venous sampling, with regard to patient acceptability, particularly in adolescents with Down’s syndrome and with regard to cost. There is growing evidence that capillary blood spot TSH is a reliable screening tool for thyroid dysfunction in children with Down’s syndrome.2–4 Capillary blood spot TSH may, in the future, come to replace venous TSH sampling in children with Down’s syndrome.