Endocrine Abstracts

Introduction: Primary congenital hypothyroidism is the most common neonatal endocrine disorder, traditionally subdivided into thyroid dysgenesis, referring to a range of abnormalities in thyroid development, and dyshormonogenesis. We report two cases of dyshormonogenesis in a brother and sister followed for congenital hypothyroidism by inactivating mutation of the TSH receptor, illustrating the good evolution in case of an adapted treatment.

Clinical cases: This is a brother and sister aged 21 and 17 years respectively, from a non-consanguineous marriage. The diagnosis of congenital hypothyroidism due to a hormone synthesis disorder was made at the age of 1 month in both of them, in view of: clinical and biological signs of peripheral hypothyroidism, the cervical ultrasound showed a thyroid gland in place, with regular contours and homogeneous echostructure, and the genetic study was in favour of an inactivating mutation of the TSH receptor. Both patients are treated with Levothyroxine, with regular intake of the treatment, and a good clinical and biological evolution with no mental retardation.

Discussion: Congenital hypothyroidism on hormone synthesis disorder is characterized by a defective molecular pathway for thyroid hormoneogenesis resulting in failure of hormone production by a structurally intact gland. Hypothyroidism secondary to TSH resistance is rare. TSH receptor abnormalities have been described first in cases of thyroid hormone resistance and then in cases of congenital hypothyroidism with an established gland in a eutopic but hypoplastic position. Delayed treatment of neonatal hypothyroidism can result in profound neurodevelopmental delay; therefore, congenital hypothyroidism is screened in developed countries to facilitate prompt diagnosis and treatment. Careful evaluation will usually reveal the etiology of congenital hypothyroidism, which can inform treatment and prognosis. Early and adequate treatment with Levothyroxine results in excellent neurodevelopmental outcomes for most patients with congenital hypothyroidism.

Conclusion: Congenital hypothyroidism is common and can result in severe neurodevelopmental morbidity. Neonatal screening is an important tool to detect congenital hypothyroidism. Prompt diagnosis and treatment are essential to optimize long-term outcomes. These two clinical cases illustrate the importance of early diagnosis and treatment for a successful outcome.