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Video transcript

- You know, when most of us think of pregnancy, we focus down here at what's going on at the level of the uterus, but a healthy pregnancy has a lot to do with a properly functioning pituitary gland up here in the brain. The pituitary gland makes the hormones that are essential for life, and in pregnancy it grows. And not just by a little but by close to 150%. A lot of that growth is due to cells call lactotrophs. These cells in the pituitary gland called lactotrophs increasing in number. Lactotrophs are these cells that make a hormone called prolactin. They make this hormone called prolactin. Prolactin stimulates breast growth and milk production, so as you can imagine, it's really important during pregnancy. That's all good but the problem is that while the pituitary gland grows substantially during pregnancy, the blood supply to the pituitary doesn't increase by as much. That kind of looks like this where if this is a normal pituitary gland, this is what a normal pituitary gland looks like, and this is its blood supply. In pregnancy, this gland is way bigger, is way bigger. But, its blood supply isn't that much greater. Throughout the pregnancy, I guess you can say that the pituitary gland is in a really fragile state. It's only receiving as much blood as it needs. No more than that. It's really pretty susceptible to being in a situation where its blood supply doesn't meet its requirements, which can lead to ischemia, or a lack of oxygen supply. Eventually it can lead to death of the cells of the pituitary gland. That death of the cells in the pituitary gland is referred to as Sheehan Syndrome. The topic of this video. When do we have to worry about all of that? We have to worry about it in any case of excessive blood loss. Any sort of trauma resulting in blood loss or in the case of postpartum hemorrhage, which refers to when you have an excessive blood loss during delivery. In those cases the pituitary gland isn't able to withstand that loss in blood supply. In addition to that, remember that whenever you have a loss of blood volume, whenever you have a loss of blood volume, the blood pressure in the body drops. The body responds to that dip in blood pressure by clamping down on all of the blood vessels, which is referred to as vasoconstriction. The body repsonds to the dip in blood pressure by vasoconstricting to increase the blood pressure. That clamping down on the blood vessels of the pituitary further reduces the amount of blood that's going into the pituitary gland. In situations of acute blood loss, again such as in trauma or a postpartum hemorrhage, you can have death of the pituitary cells. What does that mean? Why is that significant if you have death of the pituitary cells? Firstly, keep in mind that this isn't an all or none type of picture. You can have death of a few, many, or all of the cells. Usually it's just the lactotrophs that die. In which case you end up with a prolactin deficiency. Because of that, if you have a prolactin deficiency, the breasts will reduce in size and the mom isn't able to breastfeed after delivery. Usually, this is actually how this syndrome is discovered. The mom isn't able to breastfeed after delivery and that warrants investigation into the cause of why that's happening. You can have the death of the lactotrophs. You can also have death of the cells that make hormones involved in the reproductive axis. That could lead to a lack of menstruation or an inability to regrow shaved pubic hair or axillary or underarm hair. Or less commonly but still possible, you can have loss of all of the cells of the pituitary gland and that could lead to symptoms of low thyroid hormone such as, weight gain, cold intolerant, and you can also have symptoms of cortisol deficiency which could lead to fatigue or feeling tired, or even life threatening low blood pressure. The main treatment for Sheehan Syndrome is replacing these hormones that you've lost at the levels that the body would normally make them. We're getting better and better at preventing this disease from occurring all together. Nowadays, we take simple measures to make sure that if the mom suffers, any form of acute blood loss, we replace that blood volume as quickly as we can. That's a little bit of information on Sheehan Syndrome.