Objective: Estriol is the main estrogen in pregnancy, but has received less attention outside gestation. It is well known that pregnancy has an immunosuppressive effect on many autoimmune diseases such as multiple sclerosis, psoriasis, thyroiditis, uveitis, and rheumatoid arthritis. Emerging evidence indicates that estriol has potential immunomodulatory benefits for many disease states including autoimmune, inflammatory, and neurodegenerative conditions. In this review, we discuss emerging roles for estriol in the treatment of menopausal symptoms, osteoporosis, cancer, hyperlipidemia, vascular disease, and multiple sclerosis. Estriol appears to offer a potentially cost-effective approach to a variety of conditions and may offer a wide range of health benefits.
Methods: We reviewed the English language MEDLINE literature with estriol in the title with emphasis on publications including nonpregnant females between January 1974 and August 2016. Approximately 393 such articles were considered and 72 articles have been referenced in this review.
Results: Estriol offers considerable benefits for postmenopausal women with reduced risks that are normally associated with traditional hormone therapies. These benefits include improved control of menopausal symptoms and better urogenital health. Moreover, the immunomodulatory role of estriol in reducing proinflammatory cytokines may be an important new therapeutic option for chronic autoimmune and neurodegenerative illnesses. Since it is a relatively weak estrogen, there is potential for use in men for conditions such as multiple sclerosis.
Conclusions: We conclude transvaginal estriol potentially offers a suitable physiologic delivery and cost-effective alternative to currently available estrogen regimens in selected patients. Additional studies on mode of delivery, safety, and efficacy merit further investigation.