Levonorgestrel intrauterine system for endometrial protection.

Progestogen is added to estrogen in hormone replacement therapy solely to provide endometrial protection, so it is logical to deliver it to its site of action. The levonorgestrel intrauterine system, which delivers 20 mug levonorgestrel per day, is now licensed for use as the progestogen component of continuous combined hormone replacement therapy. No cases of endometrial hyperplasia or carcinoma, and no significant increase in endometrial thickness, have been reported in clinical trials. The bleeding profile is similar to that obtained with other types of continuous combined hormone replacement therapy. The levonorgestrel intrauterine system thus provides a potentially bleed-free alternative to sequential therapy for perimenopausal women.