RESUMEN
<p><b>OBJECTIVE</b>To investigate the changes in local endometrial contents of estrogen receptors (ER) and progesterone receptors (PR) after insertion of levonorgestrel-releasing intrauterine system (LNG-IUS) and evaluate the efficacy of LNG-IUS in treating endometrial hyperplasia.</p><p><b>METHODS</b>The endometrial histological changes were observed in 25 anovulatory women with dysfunctional uterine bleeding after insertion of LNG-IUS, and the contents of ERs and PRs in the endometrium were measured by immunohistochemistry.</p><p><b>RESULTS</b>The endometrial proliferation activity was obviously inhibited 6 months after LNG-IUS insertion with decreased endometrial glands, glandular dysplasia and decidualization of interstitial cells. The positive cell rate for ERs and PRs in the glandular epithelial and interstitial cells were significantly reduced after LNG-IUS insertion.</p><p><b>CONCLUSIONS</b>LNG-IUS can reduce ER and PR expressions in the endometrium and inhibit endometrial proliferation, and therefore can be effective in treating simple and complex endometrial hyperplasia.</p>