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Asked by anon-181559 on 6 Jun 2018.
Question: I've heard of a rare blood disease where the blood doesn't clot properly. I don't know what it's called but I would like to know more about it
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Jason Chu answered on 6 Jun 2018:
You might be thinking of Haemophilia, a genetic disease where the body is unable to make blood clots to stop bleeding.
The genetic mutation associated with this, stops the body from producing factors that help with the clotting process.
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Alex Haragan answered on 8 Jun 2018:
There are many conditions where the blood doesn’t clot properly. Quite a few have funny sounding names!
These fall under the general category of “bleeding disorders” and as ever, biology is very complicated!
As Jason has said haemophilia is probably the best well known disorder. There are actually two types of haemophilia – type A, and type B (also known as christmas disease – named for the first person who had it, nothing to do with christmas!). These are both genetic diseases that are on the X chromosome so are more common in males.
von Willebrands disease is another (but actually there are over 20 different types of this)
Other diseases involve leaky blood vessels include Henoch-Schonlein purpura (HSP), osler-weber-rendu syndrome, and ehlers-danlos syndrome (which I list just because I like the names of them)
There are many other causes – but I suspect you probably are thinking of Haemophilia type A.
As Jason has said – clotting blood requires a number of “clotting factors”, which results in a complex system. Haemophila A specifically results in a lack of Factor VIII.
Many years ago this meant most people didn’t live much beyond late childhood- but these days we are able to make Factor VIII and replace it (and there are cleverer treatments as well).
If you want to read more the haemophilia society is a charity with a website with lots of good information like this (http://haemophilia.org.uk/wp-content/uploads/2017/04/Understanding_haemophilia_WEB.pdf)
Comments
anon-181559 commented on :
Wow! I can’t believe I didn’t know this! Thank you so much
anon-181559 commented on :
Follow up question: does it affect a female period at all??
Alex commented on :
Hi Kalik-
Yes it does. Haemophilia, due to the genetics, is rarer in females, but females do also get it. Any form of bleeding is affected – and this includes menstrual (period) bleeding.
There are varying severities – and in the days before we could make Factor VIII for most females with haemophilia, reaching puberty was, unfortunately, something of a death sentence.
Happily we have good treatments now – but it is worth remembering that many of the poorer and war-torn countries around the world struggle to access these, so people are still dying of this, completely unnecessarily.
anon-181559 commented on :
Oh my goodness! It’s weird to think you could die from that! How much blood do we actually have in our body and how much would you have to lose to die??
Alex commented on :
Hi Kalik – sorry I missed your response!
The amount of blood we have in our bodies does vary slightly – (a 50kg old lady has far less than a 140kg marine).
But roughly speaking we have around 8 pints (or about 4-5 litres). If you donate blood they take about a pint, roughly an 1/8th and that is enough to make you feel quite light headed!
How much you need to lose to die also varies – an elderly unwell person with many problems might struggle to lose even half a pint and do well, whereas a young fit person could probably lose quite a bit, as much as half, though I’ve come across cases of people losing even more and still surviving – though in both cases you’d need ITU and a lot of blood transfusions to survive!
Without medical help you wouldn’t want to lose much more than say a quarter.
But there is a quite a bit in your body!