Endometrial prostaglandins and menorrhagia: influence of a prostaglandin synthetase inhibitor in vivo.

Prostaglandin levels in the human endometrium were determined on day 2 of the menstrual cycle in eumenorrheic subjects and in patients with menorrhagia, dysmenorrhea, or both. Menorrhagic subjects had significantly higher levels of endometrial prostaglandins of the E and F series when compared with eumenorrheics. Prostaglandin E levels were markedly higher than prostaglandin F. In 10 menorrhagic subjects who completed a double-blind clinical study on the effectiveness of mefenamic acid in lowering menstrual blood loss, 9 exhibited statistically significant reduction in endometrial prostaglandin levels. A decrease in menstrual blood loss was also noted during mefenamic acid treatment in these patients. These findings are consistent with the concept that abnormally high uterine prostaglandin levels may be an important etiologic factor in menorrhagia and support the notion that one of the mechanisms of action of nonsteroidal anti-inflammatory agents in the treatment of this menstrual disorder is inhibition of endometrial prostaglandin production.