ESPE Abstracts

Background: Neonatal TSH screening program for congenital hypothyroidism (CH) in Central Serbia was introduced in 1983. Over the past three decades, increasing overall incidence rate of children with both permanent and transient forms of CH has been observed.

Objective and hypotheses: The aim of the study was to compare incidence of CH in the first 16 years of screening (period 1) with the last 15 years of screening (period 2). We also investigated the impact of the TSH cutoff change on incidence of CH.

Method: From 1983 to 1998 TSH cutoff measured by IFMA was 15 mU/l. From 1999, TSH was measured by DELFIA: from 1999 to 2006 cutoff was 10 mU/l and from 2007 was 9 mU/l. Overall incidences were calculated, and period 1 and period 2 were compared.

Results: In the period 1, a total number of 131 newborns with CH have been detected resulting in incidence of 1:5655. During this period, frequency of transient CH was 0.8%. In the period 2, CH was detected in 285 newborns (incidence 1:2829) with frequency of transient forms of 8.0%. This increase in number of transient CH in period 2 compared to period 1 was statistically highly significant (P<0.01).

Conclusion: The results of our study revealed significant increase in incidence of both permanent and transient forms of CH related to lower cutoff. Further investigations are needed to reveal other contributory factors important for increasing incidence of CH in Serbia.