Extrathyroidal congenital defects in children with congenital hypothyroidism – observations from a single paediatric centre in Central Europe with a review of literature

Introduction
Patients with congenital hypothyroidism (CH) can have an increased risk of occurrence of extrathyroidal defects compared to the general population, which could influence their development. The abnormalities occur mainly in organ systems whose development and function is dependent on genes that are also responsible for proper organogenesis of the thyroid gland and thyroid hormone synthesis.

Aim of the study
The aim of the study was to evaluate the frequency of extrathyroidal defects in CH patients, taking into consideration the cause of this co-occurrence and the role of genetic tests.

Material and methods
The study included 54 newborns with positive screening test for CH based on elevated TSH level, in the years 2010–2017, from South-Eastern Poland. The data was retrieved retrospectively from patients’ medical records.

Results
Twenty of 54 newborns with CH (37%) had congenital defects of other organs. In 10 (18.5%) cardiac defects were found, in 5 (9.25%) abnormal symptoms of the respiratory system, 7 (12.96%) had abnormalities of the gastrointestinal system, five (9.25%) had genitouri-nary abnormalities, 3 (5.55%) had abnormalities of the nervous system, and 6 (11.1%) had musculoskeletal abnormalities.

Conclusions
The analysis of our data and current literature suggests that genetic factors play the most important role in the development of extrathy-roidal abnormalities in newborns with CH. Identifying the mutation causing CH, the potential defects that can accompany newborns with CH, screening could be offered for these patients in order to obtain an earlier diagnosis and implement early and appropriate treat-ment.