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 E₂ 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.