Etiological Evaluation of Congenital Hypothyroidism in Cases Referred from the National Screening Program

Aim: To evaluate cases referred from the congenital hypothyroidism (CH) new-born screening program. Materials and Methods: One hundred and thirty-five cases which were referred between January 2017 and July 2019 were included in the study. Results: Fourty eight of 135 cases (35.6%) were diagnosed as CH. The mean onset of treatment was 17.31 +/- 9.92 days. Clinical findings suggesting hypothyroidism were detected in 27 patients (56.2%) and goiter was detected in 2 patients (4.1%). According to imaging findings, 16 (35.5%) patients were diagnosed as dysgenesis, [1 (2.2%) as agenesia, 3 (6.7%) as ectopia, and 12 (26.6%) as hypoplasia], 11 were diagnosed as dyshormonogenesis (24.5%), and 18 were diagnosed as eutopic thyroid (40%). The mean levothyroxine dose was 12.7 +/- 2.5 mcg/kg/day and the mean onset of treatment in 30.4% of diagnosed patients was within the first 14 days and 93.3% were within the first 30 days. Conclusion: Dysgenesis and dyshormonogenesis are the most common detectable causes of CH. The normal localization of the thyroid gland in about half of the patients suggests that transient causes of CH may be more common than expected. Considering that only 1/3 of the patients were treated in the first 2 weeks, it was thought that the referral of patients is still an important problem and it should be done more promptly.