Adjustment of levothyroxine during pregnancy in women undergoing thyroid carcinoma surgery / 中华内分泌外科杂志

ABSTRACT

Objective Hypothyroidism during pregnancy has been associated with impaired cognitive development and increased fetal mortality.In this retrospective study we attempt to identify the timing and adjustment of levothyroxine during pregnancy.Methods 20 women planning pregnancy after thyroidectomy because of thyroid cancer were observed before and throughout their pregnancies.Their thyroid function was measured before conception,and approximately every 4 weeks during pregnancy.The dose of levothyroxine was increased to maintain the thyrotropin concentration at preconception values throughout pregnancy.Results 21 pregnancies occurred in the 20 women and resulted in 20 full-term births.One woman had abortion.Their basal dose was all 100 μg.The dose increased by 12.5 μg a time to target the thyrotropin concentrations (0.1-0.25 mU/ml).The mean levothyroxine requirement increased 50 percent during the first half of pregnancy and plateaued by the 16th week.This increased dose was required until delivery.All the newborns and their mothers were healthy according to the follow-up.Conclusions We propose that women after thyroid cancer surgery should increase levothyroxine dose as soon as pregnancy is confirmed.Thereafter,serum thyrotropin level should be monitored and the levothyroxine dose adjusted accordingly.The adjustment dose is set at 12.5 μg and the maternal thyrotropin concentration is between 0.10 and 0.25 mU/ml,which guarantees healthy growth of fetus while suppresses thyroid tumor growth simultaneously.