[In Process Citation]

GnRH agonist (GnRHa) administered for 6 months leads to an effective desensitisation of the pituitary and hypoestrogenism without exerting a particular effect on the whole metabolism. At the end of the first month's a suppression of the serum estradiol levels are achieved, the level of LH and FSH decline in the hypogonadotropic range. No negative influence on the lipid metabolism after administration of GnRH agonist has been observed. The balance of HDL/LDL does not change during the treatment. There were neither any negative changes in the liver metabolism, kidney function nor in the electrolyte values. In anaemic premenopausal women, for example due to serious menstrual problems, a normalisation of the haemoglobin concentration is obtainable already after a 12-week treatment. With regard to the hemostatis system a significant reduction of the procoagulant activity, fibrin turnover rate and a significant improvement of fibrinolytic activity can be observed under a GnRHa therapy. Although the use of GnRHa leads without doubt to a drastic reduction in the uterus blood flow there are no signs that this also leads to a change in the cerebral arteries blood flow. Menstrual bleeding occurs on average 3 months after the last injection of an GnRHa depot injection; with daily injection or nasal spray 3 to 4 weeks earlier. Theoretical considerations as well as the world-wide use as part of the infertility treatment--in some countries more than 90% of all IVF-cycles are performed using GnRH--,contradict the fact that GnRHa cause a teratogenic effect. Domineering undesirable side-effects during a treatment with GnRH can be traced back almost exclusively to the effective hormonal deprivation. In this context it is remarkable which percentage patients complain about trouble of this spectrum before GnRHa treatment is initiated. The chronicle reduction of the sexual hormone level leads without a doubt to a reduction of bone mineral density. The clinical relevance is furthermore a matter of controversial discussion. Prevention measures can be undertaken through an add-back therapy. This can also be of help in the case of vegetative side-effects caused by a decrease in sexual hormones. The question arises to what extent effective non hormonal add-back therapies are at disposal in the treatment of sexual hormone related malignant tumours. Also men with testosterone deprivation can suffer from distinctive hot flushes, sleeping disturbances and depression which requires some kind of relief in order to maintain an acceptable quality of life.