School based screening for hypothyroidism in Down's syndrome by dried blood spot TSH measurement

摘要

OBJECTIVE—To determinethe feasibility of annual hypothyroid screening of children withDown's syndrome by measuring thyroid stimulating hormone (TSH) ondried blood spots at school, and to describe the outcome in positive children.
DESIGN—Establishmentof a register of school children with Down's syndrome, and proceduresfor obtaining permission from parents, annual capillary blood samples,TSH measurement, and clinical assessment of children with TSH values> 10 mU/litre.
SUBJECTS—All schoolage children with Down's syndrome within Lanarkshire and GlasgowHealth Boards during 1996-7 and 1997-8.
RESULTS—200of 214 school children with Down's syndrome were screened. Four of theunscreened children were receiving thyroxine treatment, and only 5 remained unscreened by default. 15 of the 200 children had capillaryTSH > 10 mU/litre, and all but 1 had evidence of Hashimoto'sthyroiditis. Seven of the 15 children started thyroxine treatmentimmediately, 6 with a pronounced rise in venous TSH and subnormal freethyroxine (fT4), and one with mildly raised TSH and normal fT4 butsymptoms 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.