127 THYROID STIMULATING HORMONE LEVEL CHANGE DURING CONTROLLED OVARIAN STIMULATION

Abstract

Women who undergo assisted reproductive technology (ART) are exposed to a supra-physiological hormonal environment, which can affect the hypothalamus-pituitary-thyroid axis. Understanding these changes can help us improve the outcomes of ART. In this study we discuss the changes of thyroid hormone levels during ovarian stimulation as part of intrauterine insemination (IUI) and compare hypothyroid and euthyroid patients. Fifty-two infertile women aged 22 to 40 who underwent induction ovulation (I/O) as part of IUI were enrolled in this study. Out of 52 patients, 13 had underlying thyroid disease receiving levothyroxine treatment, and their thyroid test results were normal (<2.5) for more than 6 weeks and had taken fixed levels of levothyroxine for more than 6 weeks. The TSH levels were measured by electrochemiluminescence at 3 times: baseline TSH (before starting of I/O), the day of HCG administration, and 4 weeks after. The change of TSH levels during this period and its relationship with baseline hypothyroidism, oestradiol levels, and I/O and pregnancy outcome were studied. Mean central index, frequency percentage, the median, and dispersion of standard deviation and interquartile range (IQR) were used to describe the data. Statistical tests, including t-test and chi-square, were used to analyse the data. Mean difference and relative risk indices were used to measure the differences. There was a significant increase in TSH level at the time of hCG injection compared with basal TSH in hypothyroid patients under treatment, TSH increased from 1.61 ± 0.81 to 2.75 ± 1.86 (P = 0.045), and this increase was seen in TSH 4 weeks later from 1.61 ± 0.81 to 2.12 ± 0.87 (P = 0.026). However, there were not significant changes in thyroid hormone level during treatment in euthyroid patients. In hypothyroid patients who got pregnant, there was no significant increase in 3 TSH measurements. But for the patients with an unsuccessful cycle this increase was seen at the time of HCG injection and 4 weeks later in comparison with basal TSH, which was statistically significant: 1.55 ± 0.83 v. 2.97 ± 2.09 (P = 0.05) and 1.55 ± 0.83 v. 2.14 ± 0/99 (P = 0.039). But this change was not seen in euthyroid patients with successful and unsuccessful cycle results. The relationship between TSH level with oestradiol in both euthyroid and hypothyroid patients was not significant. There was not a significant correlation between the number of follicles bigger than 16 mm, the mean size of follicles, and endometrial thickness with TSH at the time of HCG injection in both hypothyroid and euthyroid patients. There was a negative and reverse correlation between endometrial thickness and TSH at the time of HCG injection, but it was not significantly different. (P = 0.05). In euthyroid patients who undergo I/O as part of IUI, we did not observe significant TSH level changes during I/O, but in controlled hypothyroid patients a rise in serum TSH levels was observed. The pregnancy rate between 2 euthyroid and controlled hypothyroid groups was not different.