Mirena in the treatment of idiopathic menorrhagia
Idiopathic menorrhagia is defined as when menstrual blood loss is >80 ml in the absence of organic pathology. Idiopathic menorrhagia is usually associated with ovulatory cycles although if there is heavy or erratic bleeding this may indicate anovulatory cycles (i.e. menstrual cycles where ovulation fails to occur)1.
How Mirena works in treating idiopathic menorrhagia
Mirena can prove to be an effective treatment for menorrhagia. This is because levonorgestrel is a very potent blocker of estrogen activity on the endometrium2. (See also How does Mirena work? in Contraception section.) The effect of LNG in the uterine cavity is that it gradually reduces the thickness and vascularity of the endometrium over an initial 3-6 months of use. As a result of this suppression of the endometrium, most women experience reduction of blood loss but its therapeutic significance is greatest in women with menorrhagia3.
Considerations before prescribing Mirena
It’s important that before using Mirena as a treatment for idiopathic menorrhagia, patients should initially be investigated for an underlying cause such as endometrial hyperplasia or cancer, fibroids and polyps, pregnancy complications and iatrogenic reasons (e.g. medications). Investigative options include blood tests, ultrasound scan, hysteroscopy and endometrial biopsy4.
Other treatment options for idiopathic menorrhagia
Current pharmaceutical options to treat menorrhagia include non-steroidal anti-inflammatory drugs (NSAIDs), (e.g. mefenamic acid), antifibrinolytics (e.g. tranexamic acid), danazol, progestogens and combined oral contraceptives. The surgical alternatives include hysterectomy and endometrial ablation or resection.
(See section on Efficacy and Safety for information on how Mirena compares with other treatments for menorrhagia.)