Lower TSH Cutoff Level for Congenital Hypothyroidism Neonatal Screening: Pilot Experience in the Buenos Aires City Neonatal Screening Program (PPN)

VIEITES A; ENACAN R; GOTTA G; ROPELATO G; JUNCO M; MACCALLINI G; DRATLER G; GLIKMAN P; ONETO A; ODRIOZOLA A; MICENMACHER V; DURE A; MUNTAASBKI P; ARANDA C; CHIESA A

Santiago

Congreso; X Latin American Congress of Inborn Errors of Metabolism and Neonatal Screening.; 2015

Sociedad Latinoamericana de Errores Congenitos del Metabolismo y Screening Neonatal

Introduction:A lower TSH cutoff level in the neonatal screening for congenital hypothyroidism (CH) would increase both detection and recall.Objective:We report recall changes and characteristics of detection in the pilot experience carried out by our Neonatal Screening Program for CH lowering TSH cutoff level from 10 to 8 mUI/l blood.Population and methods:From 1/6/13 to 31/5/15, CH screening was performed measuring TSH (IFMA-DELFIA) in dried blood spots. Children with TSHbetween 8 and 10 mUI/l blood were recalled and evaluated by a pediatric endocrinologist. Serum TSH,T4,FT4,T3, thyroglobulin and antithyroid antibodies were determined. All of them were followed until confirming or eliminating the diagnostic suspicion.Results:59.887 newborn were screened, 218 recalled withTSH >10 mUI/l blood and 52 CH were detected. Recall rate (RR):0,36%. With the new cutoff 55 extra newborns were recalled (24 girls, 52 at term, 11 exposed to iodide), RR:0.45%. Six (10%) came between 45 and 101 days of life withnormal thyroid profile. The remaining 49 were seen at a medianage of 12 days(Range:6-25). 46/49 (93%)hadTSHandthyroidhormones in the normal reference range for age before the firstmonth of life (36 with a single evaluation) and did not requiretreatment. Three babies had persistent elevated TSH. Diagnosesof stable hyperthyrotropinemia was achieved in two patients(TSH: 10 and 12 mUI/l with normal thyroid hormones and eutopic gland in TC99 scan). The third presented transient hypothyroidism with goiter (TSH:25.7mUI/I, T4:10.8ug/dl,F4L:1.51ng/ml, negative antibodies). Treatment was started for 3 months andaccidentally withdrawn, finding complete recovery of thyroidfunction (followed up for 9 months). No relationship was foundbetween diagnosis, gestational age, exposure to iodide or autoimmunity. Conclusion:With the new cutoff, RR is still acceptable for a neonatal screening program. 95%of the recalledbabies reached a normal thyroid profile within the first monthof life. This strategy allowed the identification of newborns witheither functional and/or transient thyroid disorders not related toprematurity, iodide or autoimmunity that represent a mild variant of the CH spectrum. This experience has to continue to drawout definitive conclusions about objectives and strategies for CHdetection in our program.