ESPE Abstracts

Background: Congenital hypothyroidism (CH) is divided into two main groups as ‘permanent’ and ‘transient’. Diagnosis of transient hypothyroidism is important to avoid lifelong unnecessary therapy with its possible side effects.

Objective and hypotheses: We aimed to determine the rate of transient and permanent congenital hypothyroidism of the newborns referred to our clinic from the neonatal screening program in this study.

Method: Of the newborns who were referred to our clinic due to TSH elevation from the neonatal screening program, those who were diagnosed with CH and started to be treated were included in the study. The treatments of the patients whose treatment dose required was reduced to under 1 μg/kg per day were terminated and those who were followed up monthly and whose fT₄ and TSH levels were normal at least three times without treatment were considered to have transient hypothyroidism. The clinical and laboratory findings of the patients with transient and permanent hypothyroidism in the admission and follow up were compared.

Results: 114 of the 256 (44.5%) newborns referred to our clinic from neonatal screening program were diagnosed with congenital hypothyroidism. Of the CH patients, 70% (n=58) were evaluated to have permanent and 30% (n=25) transient hypothyroidism. There was no difference between the sex distribution, days of screening and application, serum T₄ levels and treatment start date for the permanent and transient hypothyroidism cases, but the neonatal and serum TSH levels, and treatment doses were found to be significantly lower in the transient hypothyroidism patients.

Conclusion: Initial measurements of the serum TSH level, and the required doses of L-thyroxine therapy for maintaining normal thyroid hormone levels, growth and development may have a predictive role for differentiating permanent forms of CH from the transient forms. Diagnosis of transient hypothyroidism is important to avoid lifelong unnecessary therapy.