Congenital hypothyroidism

Introduction: Congenital hypothyroidism (CH) is the most frequent endocrine congenital disorder. In Portugal, the universal screening was started in 1981/82, by TSH assay performed between the 3th and 6th day of life. Values under 10mU/L are considered normal, and between 10-20 mU/L are suspicious, and it is necessary to determine T4 in the same sample. If T4 is less than 6,5 mu g/d1, the suspicion is confirmed and the newborn is then recalled. Purpose: To review the related literature in order to establish the state of the art of CH, particularly in relation to diagnosis and treatment approach. We propose a follow up scheme for these patients to allow a more uniform approach to clinical practice. Methodology: Systematic research in the electronic databases Medline and Pubmed with the keyword: congenital hypothyroidism, including studies published up to December 2012. Conclusion: Genetic mutations responsible for CH are divided in two major groups. One group accounting for 85-90% of the cases is related to structural changes of the thyroid gland, known under the common designation of thyroid dysgenesis and occurring mainly sporadically; the other group of patients with CH suffer of functional changes in the synthesis of the thyroid hormones (hormonogenesis), which altogether represents 10-15% of the cases and are transmitted in an autosomal recessive manner. The diagnosis should be confirmed by conventional thyroid function tests. Levothyroxine must be started as soon as possible, with the goal of achieving normal T4 in two weeks and normal TSH in one month. The follow-up should be done at regular intervals of three months during the first 3 years of life. In conclusion, it is extremely important to diagnose CH during the first days of live. Treatment should be started immediately in order to avoid an impairment of the cognitive development. (C) 2013 Sociedade Portuguesa de Endocrinologia, Diabetes e Metabolismo. Published by Elsevier Espana, S.L. All rights reserved.