ESPE Abstracts (2016) 86 P-P1-897

Congenital Hypothyroidism: The Use of a TSH Cut-off Limit of 6mU/L and the ESPE Criteria for LT4 Treatment Leads to the Diagnosis of Mild but mostly Permanent Forms of Hypothyroidism

Anna Gikab, Alexandra Iliadia,b, Dimitris Platisb, Vasiliki Gioglib, Jessica Arditia, Flora Tzifia, Taxiarchis Kyrimisa, Ioannis Vasilakisa, George Chrousosa, Panagiotis Girginoudisb, Christina Kanaka-Gantenbeina & Antonis Voutetakisa

aFirst Department of Pediatrics, University of Athens, School of Medicine, “Aghia Sophia” Children’s Hospital, Athens, Greece; bDepartment of Biochemical Laboratories, Institute of Child Health, Athens, Greece

Background: Since the initiation of neonatal screening programs for Congenital Hypothyroidism (CH) in the 1970’s, a gradual decrease of TSH cut-off limits has been observed worldwide. Nevertheless, lack of universal consensus has led to wide variation of cut-off limits and LT4 therapy criteria among screening programs, even within the same country. The Greek neonatal CH screening program is carried out by a single laboratory that uses one of the lowest cut-off limits worldwide.

Objective and hypotheses: To assess the effect of using a TSH cut-off limit of 6 mU/L in Guthrie cards.

Method: The data of CH neonates born in 2009 were reviewed. At study initiation, all children were at least 6 years old and, therefore, characterization of CH as permanent or transient could be considered reliable.

Results: From a total of 120.852 newborns screened for CH in 2009, LT4 treatment was initiated in 324 (~1 in 10 recalled). Data from 224 patients were available for analysis. Patients were divided in three groups according to the Guthrie card’s TSH value: <10, 10–30 and >30 mIU/L (67%, 19% and 14% of total). CH proved transient in 41.5% (girls 35.6% and boys 45.5%), 35.7% (girls 42% and boys 28%) and 9.7% (girls 5% and boys 18%), respectively. We emphasize that 92% of patients in the <10 mU/L group, started LT4 treatment according to the latest ESPE criteria.

Conclusion: Use of a TSH cut-off limit of 6 mU/L in the CH screening program identifies milder but mostly permanent CH cases. If the screening program does not identify neonates with TSH levels between 6–10 mU/L in Guthrie cards, a substantial number of patients who fulfill the ESPE criteria for LT4-initiation will not be uncovered. Hence, the use of such low cut-off limits proves valuable with respect to the diagnosis and treatment of CH.