Thyroxine replacement during super-ovulation for in vitro fertilization: a potential gap in management?

Objective: Our objective is to report observed changes in thyroid-stimulating hormone (TSH) in two patients undergoing super-ovulation for IVF.

Design: Case report.

Setting: Private assisted reproduction practices.

Patient(s): Two hypothyroid women taking thyroxine replacement therapy undergoing super-ovulation for IVF.

Intervention(s): Laboratory records for TSH taken during ovulation induction cycles were retrieved retrospectively for six cycles and measured prospectively for one cycle each in both women.

Main Outcome Measure(s): To document changes in thyroid status during super-ovulation.

Result(s): Despite being euthyroid at the start of the super-ovulation cycle, both patients demonstrated a rise in TSH to hypothyroid levels during ovulation induction, even in the absence of ongoing pregnancy.

Conclusion(s): High circulating E(2) during super-ovulation for IVF induces increased thyroxine-binding globulin binding of thyroxine. In women taking thyroxine replacement therapy, hypothyroidism develops during a super-ovulation cycle. Whether such acute biochemical hypothyroidism is a hindrance to ovum quality, fertilization, conception, or ongoing pregnancy and whether thyroxine dose adjustment during a super-ovulation cycle would improve IVF outcomes requires further study. These case studies identify a potential management gap in assisted reproduction for women taking thyroxine therapy.