Mid-luteal serum inhibin-A concentration as a marker of endometrial differentiation.

<bold>Background: </bold>Recent studies have indicated that the corpus luteum is a major source of circulating inhibin-A and serum concentrations of inhibin-A may reflect the human luteal function. The present prospective study was undertaken to determine the usefulness of mid-luteal serum concentrations of inhibin-A as markers of endometrial receptivity (as assessed by histological dating and alphavbeta3 integrin expression) and whether they are better predictors of endometrial function than serum progesterone.<bold>Methods: </bold>Consecutive infertile women (experimental group, n = 50) with regular menstrual cycles, and fertile women who were requesting contraception and had regular menstrual patterns and normal secretory endometria (control group, n = 10) were included. In all women basal body temperature, luteal serum concentrations of oestradiol, progesterone, prolactin, and inhibin-A, and endometrial biopsies were used in the same cycle to assess luteal function.<bold>Results: </bold>Out-of-phase mid-secretory endometria were detected in 17 of the 50 infertile women. Lack of alphavbeta3 integrin expression was detected in 27 of the 50 mid-luteal endometrial biopsies. Thus, hormonal concentrations were compared in the mid-luteal phase between the following eight groups of women: group 1 (n = 10), control fertile women; group 2 (n = 50), infertile women (all); subdivided into group 3 (n = 33), with in-phase biopsies; group 4 (n = 17), with out-of-phase endometria; group 5 (n = 23), expressing alphavbeta3 integrin in endometria; group 6 (n = 27), whose endometria did not express alphavbeta3 integrin; group 7 (n = 18), with both in-phase endometrial biopsy and alphavbeta3 integrin expression; and finally group 8 (n = 12), whose endometria were out-of-phase and did not express alphavbeta3 integrin. Mid-luteal serum concentrations of oestradiol, progesterone, prolactin, and inhibin-A of the seven infertile groups were similar to those of the control group of fertile women. No statistically significant difference between the infertile groups was observed for any hormonal parameter considered.<bold>Conclusion: </bold>Mid-luteal serum inhibin-A determination does not accurately reflect endometrial function/maturation and it is not a better indicator of endometrial luteal phase dysfunction than mid-luteal serum progesterone. [ABSTRACT FROM AUTHOR]