When you give blood . . . .

How much does your hemoglobin count drop?

I ask this question because I gave today. Periodically the Red Cross refuses me because my red cell count is below their limit, around 117. Periodically they accept me because it's above their limit, which is 125. Today was one of the acceptance days. But it got me thinking.

It's not hard to work out that the days when I fail the test are after a period. But I'm darned sure I've never lost as much blood from natural causes as the Red Cross takes from me. It's not like I mistrust them or think the new low would be dangerous. I'm just curious. If a mere menstrual cycle can drop you 10 points in the count, what does giving about three cups of blood do?

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Originally Posted by tokolosh

How much does your hemoglobin count drop?

I ask this question because I gave today. Periodically the Red Cross refuses me because my red cell count is below their limit, around 117. Periodically they accept me because it's above their limit, which is 125. Today was one of the acceptance days. But it got me thinking.

It's not hard to work out that the days when I fail the test are after a period. But I'm darned sure I've never lost as much blood from natural causes as the Red Cross takes from me. It's not like I mistrust them or think the new low would be dangerous. I'm just curious. If a mere menstrual cycle can drop you 10 points in the count, what does giving about three cups of blood do?

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I'm confused about the figures that you stated here - 117 & 125. Normal hemoglobin in an adult female ranges between 12 & 16. Maybe the figures that you stated are actually 11.7 and 12.5, tho it doesn't make sense that they wouldn't take it if it was above 12.5

And when you donate, typically your count will drop by 1 - say if you were 13, then after donation you would probably be 12, and it would take on the average of 3-5 weeks to build back up to 13.

It is iron they test for, not hemoglobin. They only take a pint of blood from you - that's 2 cups, not three.

And every woman's body is different, some women lose a lot of iron around their menstrual cycle, others it has little to no effect. A lot depends on your diet, I for example, cannot eat most red meat because of allergies, so I have to stay healthy by making sure I get enough iron other ways.

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Originally Posted by Karen

It is iron they test for, not hemoglobin.

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They go hand in hand. If iron is low, hemoglobin will be low.

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Originally Posted by Karen

It is iron they test for, not hemoglobin. They only take a pint of blood from you - that's 2 cups, not three.

And every woman's body is different, some women lose a lot of iron around their menstrual cycle, others it has little to no effect. A lot depends on your diet, I for example, cannot eat most red meat because of allergies, so I have to stay healthy by making sure I get enough iron other ways.

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I know everyone's body is different and replenishment depends partly on diet and other factors. I wasn't wondering about that so much, just how much iron is there in a bag of blood, because once it's in the bag it isn't in ME anymore. Even allowing for varying count levels to start with, you could work out a ballpark idea of how much your score might drop right afterwards by playing with the proportions concept. I'm simply curious.

But I just called the Red Cross to find out, and it seems they don't know either :D At least the woman I asked was very surprised by the question and said she'd never thought about that before. Guess I'll just have to stay curious, or march back in and ask them to prick my finger again to satisfy my curiosity. Either way, it's a good excuse to eat clams.

You were right that it's iron they check, according to her. But then I found this statement which seems to confuse things again "Iron status is also noted by measuring hemoglobin and hematocrit levels; this is because iron is a major part of all blood cells. Blood levels of hemoglobin and hematocrit are often checked by a skin prick", which is how they do it up here.

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Originally Posted by pomtzu

I'm confused about the figures that you stated here - 117 & 125. Normal hemoglobin in an adult female ranges between 12 & 16.

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Canadian units? :p I don't know what the difference is there, but those are definitely the numbers they quoted to me and wrote down on the forms. I saw it on their little analyst-machine readout too. Could it be my mistake in saying they count hemoglobin, whereas they're actually looking at iron?

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tho it doesn't make sense that they wouldn't take it if it was above 12.5

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I think that was my fault for being unclear. They won't take your blood if you come out under 125. My 'fail' score has always been 117, for some reason. They will take your blood if you're 125 or higher, and the times when I've passed I've always been 127. Again, for reasons unknown.

But those are definitely the numbers involved.

I recently tried to give blood and I was rejected due to low iron. The Red Cross iron spec is set deliberately high so that you won't become anemic from giving blood. The requirement of minimum 8 weeks between donations is so your body can regenerate hemoglobin.

I think the Red Cross spec is 12.5 (I should remember; it was only 2 weeks ago!) Not sure of the units, though.