Repercussão dos auto-anticorpos anti-tireoidianos maternos na função tireoidiana de recém-nascidos

Abstract

As thyroid disfunctions are generally more common in females, they are expected to be found during pregnancy and to bring consequences for the fetus and the newborn. The two main consequences of maternal thyroid disease in their children are hypothyroidism and hyperthyroidism, both clinical or subclinical. Therefore, it becomes imperative to investigate the presence of maternal thyroid disease and its consequences in newborns, in order to minimize its deleterious effects. This research objectives to study the effects of maternal thyroid disease in their offspring, as well as the use of antithyroid drugs and/or inadvertent administration of radioactive iodine during pregnancy in children screening by the Programa Estadual de Triagem Neonatal PETN-MG.We conducted a retrospective cross-sectional study with children at the Clinic of Pediatric Endocrinology, Hospital das Clínicas, Universidade Federal de Minas Gerais (UFMG) that presented positive results for congenital hypothyroidism (CH) in neonatal screening and positive anti-thyroid antibodies in the first serum sample and/or who were born of mothers with known thyroid disease. We studied 34 children screened by the PETN-MG, with a positive test for congenital hypothyroidism (and 1 not screened by the program) whose mothers had positive thyroid autoantibodies thyroperoxidase (ATPO) and/or anti-TSH receptor antibodies (TRAB). TSH was measured in blood collected on filter paper and analised by ELISA method (NR< 10 UI/L). TSH, free T4 and serum ATPO by chemiluminescence (NR: 0.34 to 5.6 UI/L, 0.54 to 1.24 ng/dL and < 35 UI/mL, respectively). TRAB was measured by radioimmunoassay (NR < 10%). Twenty percent of the mothers of the children were using antithyroid drugs during pregnancy (7 patients: 41.2% from mothers with hyperthyroidism), and among their children, fourprogressed to transient hypothyroidism and 1 to permanent hypothyroidism (inconclusive etiological investigation). Analyzing antibodiess positivity and newborns outcome, between children who presented positive TRAB (21 patients), 42.9% developed permanent hypothyroidism and 28.6% transient hypothyroidism. Between 19 children who had positive ATPO, 42.1% showed transient hypothyroidism and 31.6% the permanent form. We found no correlation between newborn antibody levels (ATPO and TRAB) and their thyroid function, in other words, childrens antibody levels did not correlate with the severity of hypothyroidism nor with the values of free T4 and TSH. The survey data reinforce the need of specialized assessment (a pediatric endocrinologist) for each newborn of mother with thyroid dysfunction, since there is a known risk of disorder of this gland in this population.