Hormonal, metabolic and clinical effects of danazol in the treatment of endometriosis.

The effect of danazol in a dose of 600 mg a day was studied in 20 women with moderate or severe endometriosis. The clinical effect was found to be excellent and repeat laparoscopy after about 6 months treatment revealed a marked regression in all patients with only small residual foci of endometriosis in two of them. The side effects were few. The metabolic studies revealed a significant increase in serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), serum potassium, serum albumin and serum creatinine, but a significant decrease in serum gamma glutamyl transpeptidase (GT). Serum sodium showed no alteration. A longitudinal study of basal plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and their responses to 25 microgram gonadotrophic releasing hormone (GnRH) i.v. as well as basal plasma levels of oestradiol, oestrone, progesterone and prolactin was performed. During treatment with danazol (600 mg a day) basal levels of LH, FSH, oestradiol, oestrone and progesterone were low but did not differ from the levels found in the early follicular phase of the menstrual cycle. On the other hand the pituitary response to GnRH was significantly greater for both LH and FSH than observed during the early follicular phase. These conflicting results are discussed. It seems that danazol inhibits the pituitary secretion of biologically active LH and FSH and this action is responsible for the decreased ovarian steroid secretion. Whether the atrophy of the uterine and ectopic endometrium is an effect of the reduced oestradiol levels or is a direct effect of danazol on endometrial oestrogen receptors, or a combination of both modes of action, is not clear.