Background: TSH cut-off (CO) levels has been lowered progressively in many screening programs. Nevertheless, population detected with lower CO levels differs in severity and etiology.
Objective and hypotheses: To describe the etiological characteristics and severity of children detected by neonatal screening related to CO TSH levels.
Method: We analysed the data of congenital hypothyroidism (CH) neonatal screening performed between June 2013 and January 2016 in 4 maternities. TSH (IFMA-DELFIA) was measured in DBS obtained by heel puncture at maternity discharge (CO:8 mUI/l blood). Patients were recalled and hypothyroidism was confirmed by serum TSH,T4,FT4 and TG. Tc99 thyroid scan was performed when available. Patients were characterized as athyreotic, ectopic or eutopic, or goiter as well as with mild or severe hypothyroidism (based on FT4 levels >or <1 ng/dl). Findings were related to TSH levels intervals of detection: >20 mUI/l, 1020 mUI/l, and 89.9 mUI/l. Diagnostic efficiency (DE) was calculated for the whole program and for each TSH interval.
Results: A total of 20,441 newborn were screened, 81 recalled (Recall Rate:0.4%) and 28 confirmed diagnosis of CH (DE:34.5%). 18 patients were recalled with TSH>20 mU/L. All of them confirmed CH(DE:100%). 8 had ectopic thyroids, 3 were athyreotic, 2 had goiter, and 1 was eutopic. Etiology could not be stablished in 4. 72.2% of newborn in this group had severe hypothyroidism. 8/24 newborn recalled with TSH between 1020 uU/ml confirmed CH (DE:30%). 2 were ectopic and 4 eutopic. In 2 images were not obtained. All patients presented mild HC. Finally, 2/39 recalled babies with TSH levels between 89.9 mUI/ml (DE: 5.1%) and started follow up. Both had eutopic thyroids with hyperthyrotropinemia.
Conclusion: While higher TSH levels allowed detection of patients with dysgenesis and severe disorders with better efficiency, lower CO identified mainly mild thyroid disorders. Further evaluation will allow the better characterization of the hypothyroid spectrum and to delineate adapted guides on detection and follow up.
10 Sep 2016 - 12 Sep 2016