The need for add-back with gonadotrophin-releasing hormone agonist therapy.

The usefulness of the gonadotrophin-releasing hormone (GnRH) agonists in treating benign chronic gynaecological disorders, such as endometriosis and uterine fibroids, or pre-menstrual syndrome (PMS), is limited by their hypo-oestrogenic side effects, including bone demineralisation and vasomotor symptoms. Studies in patients receiving GnRH agonists and hormone replacement therapy (HRT) show that whilst the efficacy of GnRH agonist monotherapy in treating endometriosis and fibroids is maintained, the concomitant add-back HRT can prevent the bone loss and reduce the incidence and severity of vasomotor symptoms. However, in a study of add-back HRT (an oestrogenic plus a progestogenic agent) in severe PMS, although the efficacy of Zoladex (goserelin acetate) against oestrogen-responsive symptoms, such as mood, was still evident, progestogenic side effects still occurred. It is likely that add-back HRT may need to be tailored to individual indications.