A group of 55 women with endometriosis was studied before and during danazol therapy. An unexpectedly high proportion (36%) had a raised serum prolactin level before treatment which was reduced after 50 days of danazol (before treatment 783 \m=+-\333 mU/l; on danazol 243 \ m=+-\113 mU/l, P < 0.001). In contrast patients with normal serum prolactin levels showed no significant drop on danazol therapy. In all patients serum oestradiol was significantly reduced during treatment (before treatment 449 \ m=+-\188 pmol/l; on danazol 207 \ m=+-\117 pmol/l, P < 0.001). In one patient with hyperprolactinaemia danazol reduced both basal and stimulated prolactin levels, whereas in 5 women with normal prolactin levels we could detect no gross alteration in metoclopramide or TRH stimulated prolactin levels associated with danazol therapy. The possibility that normalisation of raised prolactin levels may be secondary to reduced oestrogens and that patients with endometriosis have an increased sensitivity to oestrogen-induced prolactin secretion is discussed.Danazol is one of the most successful medical treatments for endometriosis. Exactly how the drug improves this condition is uncertain but it is undoubtedly related to the inducement of a hypooestrogenic-hypoprogestational state. Earlier inve¬ stigations into the endocrine pharmacology of danazol suggested that it acts as a seletive antigonadotrophin but more recent studies indicate a wide range of direct effects on hypothalamic-pituitary function, steroid receptors, gonadal steroido¬ genesis and endogenous steroid metabolism (Bar¬ bieri & Ryan 1981).Detailed information on the effect of danazol on serum prolactin levels is sparse and contradictory.

Plasma testosterone and corticosterone concentrations in male rats given a diet deficient in vitamin E for 130 days were significantly lower than those in rats given the same diet supplemented with vitamin E.