Screening for neonatal hypothyroidism by thyroxine and thyrotrophin radioimmunoassays using dried blood samples on filter paper.
A routine and automatized methodology for thyroxine (T4) and thyrotrophin (TSH) radioimmunoassay (RIA) using dried blood samples on filter paper is described. T4-RIA was performed on one single dot (5 mm diameter equivalent to 4 microliters of serum) while two dots were necessary for TSH-RIA. Reference filter papers were introduced in each assay for quality control. In a preliminary study on 4,155 neonates, samples generally obtained between the 5th--7th day gave a mean 'dot-T4' of 97.95 +/- 36.04 nmol/l and a mean 'dot-TSH' of 10.19 mU/l +/- 8.25, corresponding to 2.47 mU/l of serum. Within an 18-month period (November 1976-April 1978), a total of 16.522 neonates have been screened allowing detection of three cases of congenital hypothyroidism (incidence 1 : 5507), two cases of congenitally low TBG and thirty-three cases of transient hypothyroidism.
D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000097:blood / Q000175:diagnosis*; D008297:Male; D011863:Radioimmunoassay / Q000379:methods; D013048:Specimen Handling / Q000379:methods; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*
D013972:Thyrotropin; D013974:Thyroxine