Propylthiouracil-induced agranulocytosis in the third trimester of pregnancy.

Background: Thionamide-induced agranulocytosis in pregnancy is a rare event that poses unique therapeutic challenges.
Case: A 37-year-old woman developed agranulocytosis while taking propylthiouracil in the third trimester. After she took broad-spectrum antibiotics and discontinued propylthiouracil, her neutrophil counts recovered. She was initially managed expectantly but later underwent an uncomplicated total thyroidectomy at 35 weeks of gestation because of patient choice coupled with worsening thyrotoxicosis.
Conclusion: In circumstances in which thionamides are contraindicated, management options of hyperthyroidism in pregnancy are limited. The proximity to term in the third trimester makes expectant management an attractive approach when maternal thyroid indices are stable, allowing for a choice of postpartum therapies without the worry of fetal implications. However, this strategy carries risks, and thyroidectomy in the third trimester can be a safe alternative.