Marking the ‘pause

Posted by Liz on Feb 11, 2013 in aging, menopause | 0 comments

Back in 2009 and 2010, I wrote about a marker for menopause — the antimüllerian hormone (AMH) — which theoretically can accurately predict when a woman will enter menopause within a margin of three to four years. AMH is first detected in the ovarian cells when a woman is 36 weeks pregnant and continues until preimenopause. More specifically, it correlates to immature follicles in the ovaries whose role it is to house mature eggs. The greater the number of these follicles, the more likely it is that a woman will conceive. This is why AMH disappears as a women enters menopause, and why it has been identified as a marker of ovarian aging. Researchers have also discovered that women who have AMH levels that are below average for their age are likely to enter menopause up to 10 years before the average age of most women, 52 years. The importance of this cannot be overstated; one of the goals of this blog is to help you prepare for menopause and the changes that accompanying it. Hence, being able to predict when menopause may start can help you address certain potential health issues related to declining estrogen before they become full blown, e.g., elevated cholesterol.

The powers that be have recently defined two phases of the menopause transition; the early phase, in which menstruation becomes more variable and cycle length changes by 7 days or more, and the late phase, in which women miss two or more periods, experiencing at least one 60 day cycle and have elevated FSH hormone levels. These phases became the anchor for the AMH study because they allowed the researchers to weigh its potential as a marker over time. That’s exactly what  they set out to do (you can find the study published in the latest issue of Menopause.)

Using a new assay testing kit that appears to be more sensitive than its predecessors, they selected 44 women from a pool of 595 whose blood samples were taken randomly over a six year period and measured AMH. It was important that these women met criteria that would allow their AMH to be accurately measured; these included being over age 40 and menstruating regularly when they first had blood drawn, or having regular then irregular periods, not taking any medication that might affect their menstrual cycles and providing ample number of samples (at least three) over a five year time period.

The findings? Roughly three years before women entered what is considered the late stage menopausal transition,  AMH blood levels became virtually undetectable. Moreover, the proportion of women with undetectable AMH levels constantly increased, which supports the hypothesis that AMH levels below a certain point may predict progression into the late phase of the menopausal transition. Similarly, over the time course of the study, the percentage of women with low AMH levels increased by about 71% as they approached the late menopausal transition.

The numbers in the study were small so the results, while important, stil need to be borne out in larger sample sizes. But, it appears promising that AMH can detect menopause within three years, a healthy dose of reality that may ultimately prove important in disease prevention as we age.