425: Parity in relation to antithyroid peroxidase antibodies

Abstract

CATHERINE SPONG, DONALD MCINTIRE, KENNETH LEVENO, F. GARY CUNNINGHAM, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, National Institutes of Health (NIH), Bethesda, Maryland OBJECTIVE: Antithyroid peroxidase antibodies (TPO) are associated with chronic thyroiditis. Since hypothyroidism occurs more commonly in women, it has been hypothesized that fetal-to-maternal cell trafficking is responsible for this gender disparity. If so, this suggests a link between parity and TPO status and our objective was to evaluate the relationship between maternal parity and TPO. STUDY DESIGN: Between November 2000 and April 2003, all women who presented for prenatal care underwent thyroid screening. Excess serum was frozen and stored at 80°C. Serum samples from women without clinical hypothyroidism who had been screened in the first 20 weeks of gestation and who delivered a singleton infant weighing 500 g or more were analyzed for concentrations of thyroid peroxidase antibodies. Serum TPO levels were determined using a chemiluminescent assay (Immulite 2000 Analyzer, Diagnostic Products Corporation). Maternal parity was evaluated in relationship to positive TPO level ( 50 IU/mL). RESULTS: Serum samples from 17,298 women were tested. Of these, 1,012 (6%) women were identified with TPO. Women with TPO were older and more often parous. Figure A: After adjustment for maternal age, TPO status and parity were not related (P .92). Figure B: After adjustment for parity, TPO status and age remained significantly associated (P .001).