T Nation

BBB Read Plz


I read your self-phlebotomy thread. Anyway if test causes erythropoeisis, which increases O2 transport, why does increased RBC cause shortness of breath?

Its back. Im giving blood tomorrow.


There is a sweet spot edk. Beyond a certain point, the increase in oxygen transportation that an elevated haematocrit brings is overshadowed by the increased viscosity. Too many red blood cells makes the blood thicker, like a 'sludge' and provides more resistance to flow.

If you want to get complicated, resistance to flow is calculated by the equation: R = (8LV)/pi*r^4 (where L = length of the tube (i.e your arteries/veins), V = viscosity and r^4 is radius of the tube to the power of 4).

Total flow rate is calculated by F= (change in pressure) / resistance.

Look up the poiseuille equation if you are interested in learning more, as this equation combines the two.


I will put this simply.

more blood = more chances for O2 to go through the body.
however more blood = higher blood pressure and like was mentioned already it becomes thicker which makes it harder to pump.
this is where the loss of breath,migraines ect come from

you can help this by taking aspirin on a normal basis this thins the blood,basically you should treat yourself as if you have plague in the arteries as you will have much the same symptoms. which too much blood will then have a harder time transporting O2 so yes its a sweet spot.


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AH well thank you for explaining that. And now that I've missed my blood drive appointment perhaps I'll keep popping aspirins until I lower my doses even further.

Do you guys know how long it takes RBC to drop once test doses have been lowered??


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I could be wrong, but I had in my head that a RBC lives for ~120 days.
Its probably also worth noting that the kidneys will donwregulate erythropoetin production to reach homeostasis faster. Once the androgens are ceased, the RBCs near the end of their lifespan will get cleaned up by the spleen, the marrow will convert less progenitors to reticulocytes (immature RBCs) and your haematocrit should level out pretty fast. I'm not sure anyone could estimate exactly how long it will take, a few weeks would be my guess.