RESUMO
Fetal hyperthyroidism is a rare prenatal disease and can be life-threatening. The diagnosis is based on ultrasound in mothers with a history of Basedow-Graves' disease and elevation of thyrotropin receptor antibodies (TRAbs) levels. The treatment consists of antithyroid drugs. We present a mother with Basedow-Graves' disease, treated with radioactive iodine 16 years ago. She had an unplanned pregnancy at the age of 29 years, and an elevation of TRAbs (21 U/L) was found at the sixth week of pregnancy. At 22 weeks of gestation, fetal ultrasound displayed tachycardia, goiter, exophthalmos, and suspicion of craniosynostosis, hence methimazole was started. Concomitantly, suppressed maternal thyroid-stimulating hormone (TSH) was found. Her daughter was born at 33 + 6 weeks showing clinical and laboratory findings of hyperthyroidism. Consequently, treatment with methimazole was prescribed. Normal thyroid function was documented in the mother after giving birth. Clear explanation has not been found for the alteration of maternal TSH during pregnancy.
RESUMO
Resumen: Introducción: La causa más frecuente de hipertiroidismo congénito es la enfermedad de Basedow Graves (EG) materna, en la que anticuerpos anti receptor de hormona tiroestimulante (TSH) (TRAb) atraviesan la placenta estimulando al receptor de TSH fetal y/o neonatal para producir hormonas ti roideas. La disfunción tiroidea en estos pacientes se confirma con el aumento de las concentraciones de tiroxina (T4) y triyodotironina (T3) acompañado de niveles de TSH suprimida. Objetivos: Carac terizar la evolución clínica y bioquímica de los recién nacidos (RN) hijos de madres con EG, y sugerir recomendaciones respecto al tratamiento y seguimiento. Material y Método: Se realizó una revisión de la literatura usando la base de datos MEDLINE, identificando artículos que incluyeran más de 30 RN de madres con EG y describieran su evolución. Se agregaron además revisiones del tema enfati zando la evaluación y manejo de los hijos de madres con EG. Resultados: Se incluyeron 9 estudios de cohorte que incorporaron 790 embarazadas. Hubo heterogeneidad entre los trabajos; un porcentaje variable de los hijos desarrolló tirotoxicosis neonatal, la que fue más frecuente cuando las madres presentaron concentraciones elevadas de TRAb. El tratamiento de los RN se inició según diferentes criterios. La literatura recomienda tratar los casos de hipertiroidismo clínico y considerarlo en casos de hipertiroidismo bioquímico. Conclusión: Los hijos de madres con EG y TRAb elevados deben ser evaluados por la probabilidad de desarrollar tirotoxicosis neonatal. Se sugiere controlar función tiroidea periódicamente durante el primer mes de vida y tratar los pacientes con hipertiroidismo clínico y bioquímico.
Abstract: Introduction: The most frequent cause of congenital hyperthyroidism is maternal Graves' disease (GD), in which thyroid stimulating hormone (TSH) receptor antibodies (TRAb) cross the placenta and stimulate the fetal and/or neonatal TSH receptor to produce thyroid hormones. Thyroid dys function in these patients is confirmed by increased thyroxine (T4) and triiodothyronine (T3) levels accompanied by suppressed TSH levels. Objective: To characterize the clinical and biochemical evo lution of newborns of mothers with GD and to suggest recommendations regarding treatment and follow-up. Material and Method: A literature review using the MEDLINE database was made, iden tifying scientific articles that included more than 30 neonates of mothers with GD and described their evolution. In addition, a review of the topic with an emphasis on the evaluation and management of these patients was included. Results: Nine cohort studies were included, with a total of 790 pregnant women. There was high heterogeneity among the studies. A variable percentage of newborns deve loped neonatal thyrotoxicosis, which was more frequent in those patients whose mothers had high levels of TRAb. The treatment of newborns was initiated according to different criteria. The literature recommends treating cases of clinical hyperthyroidism and considers it in cases of biochemical hy perthyroidism. Conclusion: Children of mothers with GD and high TRAb should be evaluated due to the likelihood of developing neonatal thyrotoxicosis. It is suggested to monitor thyroid function periodically during the first month of life and treat patients with clinical and biochemical hyper thyroidism.