ABSTRACT Objectives To describe the findings of thyroid ultrasonography (T-US), its contribution to diagnose congenital hypothyroidism (CH) and the best time to perform it. Subjects and methods Forty-four patients with CH were invited to undergo T-US and 41 accepted. Age ranged from 2 months to 45 years; 23 patients were females. All were treated with L-thyroxine; 16 had previously undergone scintigraphy and 30 had previous T-US, which were compared to current ones. Results At the current T-US, the thyroid gland was not visualized in its normal topography in 10 patients (24.5%); 31 T-US showed topic thyroid, 17 with normal or increased volume due to probable dyshormonogenesis, 13 cases of hypoplasia and one case of left-lobe hemiagenesis. One patient had decreased volume due to central hypothyroidism. Scintigraphy scans performed 3-4 years earlier showed 100% agreement with current results. Comparisons with previous T-US showed concordant results regarding thyroid location, but a decrease in current volume was observed in eight due to the use of L-thyroxine, calling the diagnosis of hypoplasia into question. Conclusions The role of T-US goes beyond complementing scintigraphy results. It allows inferring the etiology of CH, but it must be performed in the first months of life. An accurate diagnosis of CH will be attained with molecular study and the T-US can guide this early assessment, without therapy withdrawal.

Resumo Objetivo: Estabelecer padrões de referência e estudar algumas características ultrassonográficas tireoidianas em um grupo de crianças eutireoidianas até os 5 anos de idade, comparando-as a crianças portadoras de hipotireoidismo congênito de mesma faixa etária. Objetivo: Trinta e seis crianças foram divididas em dois grupos – 23 eutireoidianas e 13 portadoras de hipotireoidismo congênito – e convocadas para a realização de ultrassonografia de tireoide. Dessas crianças, 17 eram do sexo feminino e 19, do sexo masculino, com idades entre 2 meses e 5 anos. Resultados: No grupo de crianças eutireoidianas (n = 23), o volume total médio da glândula tireoide foi 1,12 mL (mínimo: 0,39 mL; máximo: 2,72 mL), sendo observadas, também, glândula homogênea em 17 crianças (73,91%) e glândula heterogênea em 6 crianças (26,08%). No grupo de crianças com hipotireoidismo congênito (n = 13), o volume total médio da glândula tireoide foi 2,73 mL (mínimo: 0,20 mL; máximo: 11,00 mL). Quanto à localização da tireoide, foram encontradas 3 crianças (23,07%) com tireoide ectópica e 10 (69,23%) com tireoide tópica, sendo que, nessas últimas, 5 tinham glândula homogênea (50%) e 5, glândula heterogênea (50%). Das crianças com hipotireoidismo congênito, 6 (46,15%) apresentavam diagnóstico etiológico de disormoniogênese, 3 (23,07%) tinham diagnóstico etiológico de ectopia e 4 (30,76%) possuíam diagnóstico etiológico de hipoplasia tireoidiana. Conclusão: A ultrassonografia de tireoide, por se tratar de um método não invasivo, bastante disponível, de fácil realização, pode e deve ser realizada a qualquer momento, inclusive ao nascimento, sem preparação ou interrupção do tratamento, para auxiliar na definição etiológica precoce do hipotireoidismo congênito.

Abstract Objective: To establish benchmarks and study some sonographic characteristics of the thyroid gland in a group of euthyroid children aged up to 5 years as compared with age-matched children with congenital hypothyroidism. Materials and Methods: Thirty-six children (17 female and 19 male) aged between 2 months and 5 years were divided into two groups – 23 euthyroid children and 13 children with congenital hypothyroidism – and were called to undergo ultrasonography. Results: In the group of euthyroid children (n = 23), mean total volume of the thyroid gland was 1.12 mL (minimum, 0.39 mL; maximum, 2.72 mL); a homogeneous gland was found in 17 children (73.91%) and 6 children (26.08%) had a heterogeneous gland. In the group of children with congenital hypothyroidism (n = 13), mean total volume of the thyroid gland was 2.73 mL (minimum, 0.20 mL; maximum, 11.00 mL). As regards thyroid location, 3 patients (23.07%) had ectopic thyroid, and 10 (69.23%) had topic thyroid, and out of the latter, 5 had a homogeneous gland (50%) and 5, a heterogeneous gland (50%). In the group with congenital hypothyroidism, 6 (46.15%) children had etiological diagnosis of dyshormoniogenesis, 3 (23.07%), of ectopic thyroid, and 4 (30.76%), of thyroid hypoplasia. Conclusion: Thyroid ultrasonography is a noninvasive imaging method, widely available, easy to perform and for these reasons could, and should, be performed at any time, including at birth, with no preparation or treatment discontinuation, to aid in the early etiological definition of congenital hypothyroidism.