Background: Since the initiation of neonatal screening programs for Congenital Hypothyroidism (CH) in the 1970s, 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 cards TSH value: <10, 1030 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 610 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.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology