title: Confirmation of neonatal screening: reference intervals and evaluation of methodological changes in TSH measurement.
abstract: Neonatal reference values for serum thyrotropin are scarce and comprise only small numbers of patients. During 2006, changes were made in IMMULITE kits for TSH measurement. To validate methodological changes, 80 serum samples from patients were evaluated and to establish reference intervals, 334 neonates and infants were analyzed (divided into 4 groups). Group 1 (G1) (48-72 h of life) (n=153), group 2A (G2A) (7-10 days of life) (n=65), group 2B (G2B) (11-14 days of life) (n=35), group 3 (G3) (28-40 days of life) (n=81). Current kits overestimate TSH results by 26 to 37%; TSH (mIU/L) reference intervals (percentile 2.5-97.5) were G1 (1.1-12.7), G2A (1.8-9.8), G2B (1.1-7.1) (p < 0.03 vs. G2A), G3 (1.2-6.9). We suggest that during the second week of life, reference values should be divided into an early stage and a late stage, at least, for there to be an adequate interpretation of borderline measurements in newborn thyroid screening.
authors.affiliation: Endocrinology Unit, Department of Medicine, Hospital V. Sarsfield, Buenos Aires, Argentina.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Fideleff
authors.forename: Martha G
authors.initials: MG
authors.lastname: Suárez
authors.forename: Patricia G V
authors.initials: PG
authors.lastname: Sobrado
authors.forename: Maria L
authors.initials: ML
authors.lastname: Celadilla
authors.forename: Mario
authors.initials: M
authors.lastname: Mardyks
authors.forename: Carmen C
authors.initials: CC
authors.lastname: Rodriguez
authors.forename: Ana
authors.initials: A
authors.lastname: Jelen
authors.forename: Hugo R
authors.initials: HR
authors.lastname: Boquete
authors.forename: Hugo L
authors.initials: HL
authors.lastname: Fideleff
mesh_terms: D019963:Clinical Chemistry Tests / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012016:Reference Values; D013963:Thyroid Hormones / Q000097:blood; D013972:Thyrotropin / Q000097:blood*
chemical_list: D011933:Reagent Kits, Diagnostic; D013963:Thyroid Hormones; D013972:Thyrotropin