The role of measurement of progestagen-associated endometrial protein in predicting adequate endometrial differentiation

Abstract

Late secretory endometrium synthesizes and secretes progestagen-associated endometrial protein (PEP), which is measurable in the serum of cycling women, and has been shown to increase in concentration during the luteal phase of the normal menstrual cycle. The purpose of this study was to determine the utility of serum PEP as a predictor of normal or inadequate luteal phase endometrial differentiation. One-hundred-and-twenty-five endometrial biopsies were taken within 4 days of a subsequent menstrual period, during the course of evaluation of infertility or recurrent abortion. Twenty-one of these biopsies demonstrated glandular/stromal asynchrony. Thirteen patients exhibited 'out-of-phase' endometrial biopsies and 91 patients had 'in-phase' biopsies. Mean PEP values significantly increased from the mid-luteal phase to the late luteal phase. Mean PEP values for patients with in-phase biopsies (43.92 units/ml) were not significantly different from those with out-of-phase biopsies (25.24 units/ml, P = 0.0942). PEP values for patients with asynchronous biopsies were intermediate. Use of clomiphene citrate did not affect these results.

Potential biochemical markers of uterine receptivity

“…Traditionally biopsies have been performed late in the luteal phase, which is informative for the beginnings of the invasive phase of implantation, but gives no direct indication of events during the window of implantation. Blood tests of some endometrial proteins have been postulated to be of benefit (McRae et al, 1991), although this has not been realized. Uterine fluid lavage is another potential method to evaluate endometrial adequacy, although it is dependent on secreted markers, whose biochemical forms and concentrations may be altered by other components in the fluid and by fluid shifts within the endometrium and transudation from serum respectively.…”

Immunohistochemical markers of uterine receptivity in the human endometrium

“…Studies by Joshi and coworkers (1986) comparing the level of PEP in women with histologically normal endometrial maturation and those with inadequate endometrium (LPD), found that LPD cycles were characterized by subnormal PEP levels. In a more recent study, however, mean PEP levels for patients "in phase" were not statistically different from those with out of phase biopsies (McRae et al, 1991). It remains to be seen whether this protein will be clinically useful in the study of implantation related events.…”

Endometrial Growth Factors and Proteins*

“…It is a major secretory product of glandular epithelium during the secretory phase (reviewed in detail by Seppala et al 15,17 ) and is homologous with β-lactoglobulin, bilin-binding protein, and retinol-binding protein, although it does not bind retinoic acid. During the luteal phase, serum levels increase, 41 although they have not been useful predictors of adequate endo metrial maturation, [41][42][43] and no difference in serum levels has been found in conception versus nonconception cycles. 17 Gonadotropin-stimulated cycles, with all endometria that are histologically out of phase, stain abnormally for PP-14.…”