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Maternal thyroid autoantibodies predict fetal, neonatal thyroid status in Graves’ disease
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In mothers with Graves’ disease, levels of anti-thyrotropin receptor antibodies predict the risk for fetal and neonatal thyroid dysfunction, according to findings from a retrospective study in France.
“When managing a patient with Graves’ disease at the beginning of pregnancy, one of the main issues is prediction of fetal and neonatal dysthyroidism,” Maïa Banigé, MD, of the department of neonatology, obstetrics and gynecology at University Hospitals Paris Nord Val de Seine, and colleagues wrote. “[Anti-thyrotropin receptor antibodies] levels in the mother are one of the main predictors because their action can directly activate the fetal or neonatal thyroid gland or indirectly induce fetal hypothyroidism because relative overtreatment of the mother induces hypothyroidism.”
Ultrasound monitoring of the fetal thyroid gland can be used to detect fetal thyroid dysfunction, the researchers noted, but this is limited in two ways: No robust data define a cutoff for anti-thyrotropin receptor antibodies (TRAb) above which this monitoring could be considered mandatory, and clinicians lack the tools to predict neonatal hyperthyroidism when the neonate still has circulating TRAb and is no longer exposed to transplacental anti-thyroid drug administration.
“This question is of utmost importance because it will define to which facility the mother should be referred for delivery,” the researchers wrote.
Banigé and colleagues analyzed medical records from 417 women with Graves’ disease who tested positive for TRAb during pregnancy between 2007 and 2014 in 10 obstetric centers in Paris. Within the cohort, thyroid dysfunction was observed in 52 fetuses or newborns (12.5%). Of these, 46 fetuses had thyroid hypertrophy, 25 newborns developed clinical neonatal thyroid dysfunction and 19 children ultimately received therapy. In multivariate regression analyses, researchers found that maternal and child TRAb level was the strongest predictor of fetal and neonatal thyroid dysfunction.
Among all included women, based on maternal TRAb levels, the cutoff value of 2.5 IU/L best predicted fetal thyroid dysfunction, according to the researchers, with a sensitivity of 100% and a specificity of 64%. Based on newborn TRAb levels, the cutoff value of 6.8 IU/L best predicted neonatal thyroid dysfunction, with a sensitivity of 100% and a specificity of 94%. The researchers noted that 65% of women with a history of Graves’ disease in the cohort did not receive synthetic anti-thyroid drugs during pregnancy, but were still at risk for neonatal thyroid dysfunction.
“We clearly show in a large number of cases that there are precise TRAb cutoffs that can be used to establish the best perinatal follow-up and that fine-tuning of the mother’s thyroid status and ultrasound monitoring of the fetal thyroid should be used to avoid or predict fetal or neonatal dysthyroidism,” the researchers wrote. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.
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