Endocrine response to step-up microdose GnRH agonist

Kim, Su Kyoung; Kim, Hyo Jung; Lee, Jin Yong; Hong, Seo Yoo; Shin, Jung Hwan; Park, Cheol Hong; Park, Eun Joo; Seo, Yong Soo; Park, Won Il

Abstract

OBJECTIVE
The purpose of this study was to evaluate the endocrine response to step-up microdose GnRH agonist.
METHODS
Administration of triptorelin acetate was initiated from 2 mg and gradually increased to 50 mg during 6-day period to five normal menstruating women. Serum FSH, LH, and estradiol levels were serially measured for 6 days. The same set of experiment was duplicated after taking oral contraceptive for 3 weeks. Serum testosterone and progesterone levels were measured on day 1 and day 5 of experiment.
RESULTS
The flare of gonadotropin continued for 6 days. When subjects were pretreated with oral contraceptive, serum FSH levels 4 hrs after GnRH agonist injection were 17.35+/-7.88 mIU/mL, 11.26+/-4.81 mIU/mL, and 9.60+/-4.08 mIU/mL for day 1, 2, and 3 respectively. The FSH levels were not statistically different when pretreatment with oral contraceptive was not applied. The level of serum LH was significantly lower in the cycle, which was pretreated by oral contraceptive (32.13+/-9.61 mIU/mL vs. 14.12+/-5.63 mIU/mL for day 1, 28.95+/-3.09 mIU/mL vs. 15.76+/-9.92 mIU/mL for day 2, and 24.45+/-2.52 mIU/mL vs. 16.86+/-8.56 mIU/mL for day 3). The sign of corpus luteum rescue was found in 2 out of 5 subjects only in non-treated cycle.
CONCLUSION
Step-up microdose GnRH agonist protocol could induce persistent gonadotropin flare for 6 days and this regimen could be applied in controlled ovarian hyperstimulation especially for poor responders. The pretreatment with oral contraceptive is necessary to prevent supraphysiologic LH elevation and corpus luteum rescue.