title: Evaluation of three thyroid-function screening tests for detecting neonatal hypothyroidism.
abstract: Three thyroid-function detection methods were evaluated concomitantly for possible application as routine screening tests for the early diagnosis of neonatal hypothyroidism. Dried capillary-blood thyroxine (T4) was measured on eluted filter-paper discs for 9734 3-5-day old neonates. Serum T4 and thyroid-stimulating hormone (T.S.H.) assays from cord blood were studied as alternative screening tests on 4911 and 3733 infants, respectively. To avoid false-negative results, neonatal blood-T4 and cord serum-T4 screening methods were followed up for the lower 10th and 6th percentile, respectively. This resulted in a false-positive recall incidence greater than 92% owing to various additional factors which also influence T4 levels: thyroxine-binding-globulin deficiency, prematurity, and maternal drug ingestion. In marked contrast, cord T.S.H. as an initial screening test had a higher specificity and sensitivity for the diagnosis of primary hypothyroidism with the two affected cases, having values greater than 70 muU/ml (with only 0-24% of the screened population having values greater than 50 muU/ml). In order to avoid the impracticably high recallrate and false-positive incidence resulting from an initial T4 screening test, and to reduce the estimated follow-up recall to less than 0-2% of the screened infant population, it is recommended that infants with low T4 be selected for a supplementary T.S.H. screening test.
mesh_terms: D002196:Capillaries; D005069:Evaluation Studies as Topic; D005374:Filtration / Q000295:instrumentation; D005612:Freeze Drying; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000097:blood / Q000175:diagnosis*; D011863:Radioimmunoassay; D013960:Thyroid Function Tests / Q000379:methods*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014470:Umbilical Cord
chemical_list: D013972:Thyrotropin; D013974:Thyroxine