Estrogen and progesterone receptors of the out-of-phase endometrium in female infertile patients

To examine the role of steroid hormone receptor compartmentalization in infertile women with "in-phase" or "out-of-phase" endometrium.

Nonrandomized prospective clinical study.

A university clinic.

Twenty-nine infertile patients without evidence of endometriosis, tubal factor, male factor, galactorrhea, or hyperandrogenism were enrolled. Sixteen patients had in-phase endometrium and a P level > or = 10 ng/mL (conversion factor to SI unit, 3.18) (group A). Four patients had out-of-phase endometrium and a P level > 10 ng/mL (group B). Four patients had in-phase endometrium and a P level < 10 ng/mL (group C), and five patients had out-of-phase endometrium and a P level < 10 ng/mL (group D).

Each patient underwent determination of serum P and endometrial sampling on postovulatory days 6 to 9 based on serum LH measurement. Dating according to endometrial histology and biochemical assessment of estrogen receptor (ER) and P receptor (PR) were performed on each sample.

The level of cytosol ER was significantly lower in out-of-phase endometrium regardless of serum P level. There were no significant differences in the levels of cytosol PR and nuclear ER and PR among groups. In a long-term follow-up study, 6 of 29 patients became pregnant. The cytosol ER:PR ratio in these patients was found to fit a single straight regression line (y = 0.34x - 2.2).

Out-of-phase endometrium probably depends on inadequate cytosol ER. An appropriate cytosol ER:PR ratio may be important to become pregnant.