Evaluation of TRAb and TSI Leves and Thyroid Function in Pregnant Women With Graves’ Disease and Newborn: Preliminary Data

Introduction: GD, mediated by TSH receptor-stimulating immunoglobulins (Igs) (rTSH), can lead to fetal thyroid dysfunction through the passage of Igs through the placenta during pregnancy. TRAb levels, used for prognostic evaluation, measure rTSH-stimulating and blocking Igs while TSI evaluates only as stimulating Igs. Objective: To prospectively evaluate pregnant women with DG and newborns (NB) by measuring TRAb and TSI and their correlation with thyroid function and postpartum complications. Methods: The patients were evaluated during pregnancy and the puerperium and the respective newborns. TSH, thyroid hormones and TRAb were evaluated by electrochemiluminescent method (Roche) and TSI by chemiluminescent assay (Siemens). TRAb<1.75IU/L and TSI<0.55IU/L were considered negative. Results: Nine patients were evaluated, with a mean age of 27.4±5.7 years: 6 had TRAb and TSI positive in the 1st trimester (1st-tri), when they maintained or started DAT; one with both negative (without DAT) and one with weakly positive TSI, when DAT was suspended. These last two remained euthyroid during pregnancy and puerperium. Of the first 6, 4 were evaluated in the 3rd-tri: three negative for TRAb and maintained positive TSI, 2 in low leves and one for high titles, when DAT was suspended or reduced; one kept both at very high levels. A patient with post-DT hypothyroidism, performed 3 years ago, using levothyroxine, evaluated in the 3rd-tri, had a negative TRAb and a highly positive TSI and remained so after pregnancy. The two patients who presented weakly positive TSI in the 3rd-tri evolved with their negative results and without DAT in the puerperium. The patient with TSI in high titers evolved with elevated levels as well as positive TRAb titers and postpartum decompensation. The patient with positive antibodies remained compensated for stable doses of DAT. Four NB were evaluated: all healthy, with normal thyroid function and negative TRAb. TSI was positive in 2 in the postpartum period; TSI was negative afterwards, while in the other 2 both antibodies were negative. Conclusions: TSI was not associated with thyroid dysfunction in NB, although it was associated with worsening hyperthyroidism in pregnant women, when at high titers. Positive TSI at low levels were not associated with worsening of the condition, which requires further studies to determine the cutoff point for assessing treatment suspension.