RESUMO
OBJECTIVE: To assess the relationship between endogenous LH serum levels after GnRH analogue administration and serum P elevation on the day of hCG administration (P hCG). DESIGN: Retrospective study. SETTING: Reproductive medicine center in a university hospital. PATIENT(S): A total of 708 patients undergoing a GnRH agonist or antagonist protocol for IVF intracytoplasmic sperm injection. INTERVENTION(S): Controlled ovarian stimulation. MAIN OUTCOME MEASURE(S): Serum P values according to GnRH analogue; correlation between serum LH measurements and P hCG values. RESULT(S): Serum P hCG values were significantly lower following the GnRH antagonist than agonist protocol. A positive correlation between serum P hCG and LH area under the curve or day 6 LH values was found in the GnRH agonist group and between P hCG and LH hCG levels in both GnRH analogue regimens. With multivariate analysis, P hCG values were positively correlated with serum E(2) levels on hCG administration day and with the total FSH dose in both GnRH analogue-treated groups. Additionally, the correlation between serum P hCG and LH hCG values was positive in patients treated with the GnRH agonist protocol. CONCLUSION(S): The lower serum P levels on hCG administration day following the GnRH antagonist protocol are mainly explained by lower granulosa cell steroidogenic activity. The correlation with serum LH hCG values was positive in the GnRH agonist-treated group.