Decrease of Free Thyroxine Levels after Controlled Ovarian Hyperstimulation

Controlled ovarian hyperstimulation could lead to opposing effects on thyroid function. Therefore, in a prospective study of 65 women undergoing controlled ovarian hyperstimulation, thyroid hormones, T4-binding globulin, TPO antibodies, gonadotropins, estradiol, and PRL were measured before and after controlled ovarian hyperstimulation. After ovarian stimulation (mean ± se of mean): free T4 decreased, 14.4 ± 0.2 vs. 12.9 ± 0.2 pmol/L (P < 0.0001); thyroid-stimulating hormone increased, 2.3 ± 0.3 vs. 3.0 ± 0.4 mU/L (P < 0.0001); T4-binding globulin increased, 25.2 ± 0.7 vs. 33.9 ± 0.9 mg/L (P < 0.0001); total T4 increased, 98.1 ± 2.3 vs. 114.6 ± 2.5 nmol/L (P < 0.0001); total T3 increased, 2.0 ± 0.04 vs. 2.3 ± 0.07 nmol/L (P < 0.0001); TPO antibodies decreased, 370 ± 233 U/mL vs. 355 ± 224 U/mL (P < 0.0001); LH decreased, 8.1 ± 1.1 vs. 0.4 ± 0.1 U/L (P < 0.0001); FSH did not change, 6.5± 0.6 vs. 7.9 ± 0.9 U/L (P = 0.08); human CG increased, <2 ± 0.0 vs. 195 ± 16 U/L (P < 0.0001); estradiol increased, 359.3...