They’ll be a lot of press this week over a study conducted in the UK reporting that the levonorgestrel IUD (Mirena) is superior to usual medical treatment for the treatment of heavy menstrual bleeding (menorrhagia).
“Usual” medical treatment for 75% of the women in the UK study was tranexamic or mefamanic acid – drugs that control bleeding through the coagulation pathway, and which are not widely used in the States.
Here in the US, we tend to use oral contraceptives and progestins to treat menorrhagia. Unfortunately, the UK investigators did not break out the comparison between these hormonal treatments and the IUD, so we really don’t know how well Mirena would perform compared to usual treatment here. However, given years of seeing how effective birth control pills are in decreasing menstrual flow, I’m going to assume that they still work as well as they always have, and not necessarily better or worse than the hormonal IUD. Each method has its pros and cons, and every woman is different.
The investigators also reported that the Mirena IUD was less effective than usual treatment in women whose BMI is under 25. This is not surprising, since heavier women could have an element of estrogen excess that would be better addressed by hormonal therapy such as Mirena or birth control pills rather than anti-fibrinolyics such as Tranexamic acid.
None of this, by the way, is meant to discourage women and their doctors from using Mirena to treat heavy periods – it is indeed a very effective treatment and one that I offer my own patients.
Just trying to give the anticipated hype some context and perspective.