How much does blood donation lower your hematocrit?

[MD2B]

Curious as to everyone's experiences with how much one pint of blood donation lowers their hematocrit?

[bass]

quite a bit actually, lets say if you're at 50% then donate a pint, it could go down to 45%, but drinking lots of fluids is important to keep this number down.

[Sworder]

MuscleInk provided an excellent explanation to me on how to calculate how much your hematocrit will get lowered:

Below is a general guide only and in practice, the calculation below would not be used with any clinical guarantee (BW would be performed) - but it's a reasonable guide. I'll explain it by example:

Suppose you have a 60 kg man donating blood. His hematocrit is measured at 40 and total blood volume is 78 cc/kg body weight (for most males). His total blood volume is then 60 x 78 = 4680cc. Since the hematocrit is 40 the total volume of blood cells would be 4680 * 40% = 1872cc of blood cells in the blood (before donation).

What would the new hematocrit if 1000cc were drawn for donation? The calculation is as follows:

1000*.40 = 400cc of blood cells removed. Before donation there were 1872cc of blood cells. 400cc were removed, therefore, total blood cells after donation is 1872-400=1472cc of blood cells. The new hematocrit would be the number of blood cells after donation divided by the original blood volume or: 1472/4680=.315% or 31.5 for the new hematocrit.

[HRTstudent]

After all that calculus and algebra, I guess its safe to say "about 2-8%"?

LOL... just kidding but I've read something like that before.