Nearly one-third of women experience heavy periods each month. This means that unlike normal periods where women lose up to 40 mL of blood per cycle, some women lose as much as 80 mL (more than a quarter of a cup) in at least one cycle throughout their life. Scientists think they might have found the answer as to why this happens, and they are blaming it on a non-hormonal protein. A new
small study suggests that low levels of a specific protein known as
hypoxia-inducible factor 1 (HIF1, right) might be to blame.
HIF1 is a pretty handy healing molecule. When oxygen levels drop in parts of the body, a condition known as hypoxia, HIF1 activates more than 60 genes linked to tissue regeneration, and has already been shown to play a role in repairing the gut lining. Hypoxia also occurs in the uterus during menstruation, so it made sense to investigate whether it might also be involved in repairing the lining of the uterus during women's periods - or not, as in the case of women with heavy bleeding.
To figure this out, scientists sampled cells from the uteruses of eight women over a month - half of whom experienced heavy periods. Examining these cells, they found that HIF1 did increase in the uterus during menstruation, as they'd predicted, but the women with heavy bleeding had much lower levels of the protein than those with regular periods.
The researchers then took a group of normal mice and mice that had been genetically modified to be unable to produce HIF1, and induced them to get their periods once a month, by giving them injections of estrogen and progesterone that mirrored the human cycle. They found that 16 hours after bleeding had stopped, the uterus of normal mice were already showing signs of repair. But the mice without HIF1 showed no signs of recovery, even within a 24 hour window.
That suggests that HIF1 might play an important role in repairing the lining of the uterus to stop the bleeding, and when it's not present in high enough levels, heavy blood loss continues.
