School based screening for hypothyroidism in Downs syndrome bydried blood spot TSH measurement

摘要

OBJECTIVE—To determine the feasibility of annual hypothyroid screening of children with Down's syndrome by measuring thyroid stimulating hormone (TSH) on dried blood spots at school, and to describe the outcome in positive children.
DESIGN—Establishment of a register of school children with Down's syndrome, and procedures for obtaining permission from parents, annual capillary blood samples, TSH measurement, and clinical assessment of children with TSH values > 10 mU/litre.
SUBJECTS—All school age children with Down's syndrome within Lanarkshire and Glasgow Health Boards during 1996-7 and 1997-8.
RESULTS—200 of 214 school children with Down's syndrome were screened. Four of the unscreened children were receiving thyroxine treatment, and only 5 remained unscreened by default. 15 of the 200 children had capillary TSH > 10 mU/litre, and all but 1 had evidence of Hashimoto's thyroiditis. Seven of the 15 children started thyroxine treatment immediately, 6 with a pronounced rise in venous TSH and subnormal free thyroxine (fT4), and one with mildly raised TSH and normal fT4 but symptoms suggesting hypothyroidism. Eight children with mildly raisedvenous TSH and normal fT4 were left untreated; 1 year after testingpositive, fT4 remained > 9 pmol/litre in all cases, but 4 childrenwere started on thyroxine because of a rise in TSH. TSH fell in 3 ofthe 4 remaining children and there was a marginal rise in 1; all remainuntreated. The prevalence of thyroid disease in this population is⩾ 8.9%.
CONCLUSION—Driedblood spot TSH measurement is effective for detecting hypothyroidism inDown's syndrome and capillary sampling is easily performed at school.The existing programme could be extended to the whole of Scotlandwithin a few years.