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  #1  
Old 11-20-2002, 10:39 AM
sqweels sqweels is offline
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Can donating blood reduce high blood pressure?

Temporarily anyway?
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  #2  
Old 11-20-2002, 12:10 PM
Demo Demo is offline
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Sure, any decrease of volume within your arteriovascular system will decrease the pressure. You'll see this on people who are extremely dehydrated due to low plasma volume. We often give people IV fluids to bolster low BP.

Of course it's not a long term answer. ;-)


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  #3  
Old 11-20-2002, 12:14 PM
CalMeacham CalMeacham is online now
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It's not clear to me that you actually will have any benefit from donating blood -- your body isn't a glass bottle, after all -- it's an organic collection of sacs, with feedback and control mechanisms built in. Whatever was keeping your pressure high would, I suspect, tend to keep it high even after you lost a quantity (as long as it wasn't too much).

Side note: They won't let you donate blood if your pressure is too high. I speak from experience here.
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  #4  
Old 11-20-2002, 12:24 PM
gigi gigi is offline
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Quote:
Originally posted by CalMeacham
Side note: They won't let you donate blood if your pressure is too high. I speak from experience here.
Specifically, 180 systolic and 100 diastolic.

Here is some suggestion of a link between donating blood and reduced risk of heart disease, but it includes the idea that donors may live more healthy lives overall.
Quote:
Sometimes physical problems such as high blood pressure are found during a blood donation mini-physical. So donating blood can be a way to keep a check on your own health while helping others. Preliminary studies also found that heart attacks and other cardiac problems were less common in men who had donated blood compared to men who had not. The two studies involved over 6,500 men and were conducted by the University of Kansas and the University of Kuopio in Finland. Researchers believe by giving blood, men -- and post-menopausal women -- rid their bodies of excessive iron, which is thought to contribute to heart disease.
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  #5  
Old 11-20-2002, 12:39 PM
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Quote:
Originally posted by CalMeacham
It's not clear to me that you actually will have any benefit from donating blood -- your body isn't a glass bottle, after all -- it's an organic collection of sacs, with feedback and control mechanisms built in. Whatever was keeping your pressure high would, I suspect, tend to keep it high even after you lost a quantity (as long as it wasn't too much).
Yet the overall volume is still decreased, in turn decreasing the BP:

"Immediately after donating a unit of blood, the circulating blood volume is reduced by 9%. This will reduce the blood pressure and make the person more susceptible to fainting, one of the reasons you are escorted and watched closely immediately after donating blood, and why you are fed and forced to drink fluids. The fluid lost by donating blood is replaced in a few hours, however, divers are also prone to dehydration/fainting. "

From http://divermag.com/archives/april20...tor_apr00.html

I don't know anything about that source, but the quote above concurs with what I've been taught.
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  #6  
Old 11-20-2002, 12:56 PM
CalMeacham CalMeacham is online now
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Quote:

Yet the overall volume is still decreased, in turn decreasing the BP:
I'll take your word for it that it goes low immediately, as I have no training in this area. I'll just repeat that decreasing the volume doesn't automatically lower the pressure in a feedback system or a system in which things can mechanically adjust.-- imagine a flexible bag or, better yet, a cylinder with a piston atop it and a heavy weight. If you draw off a bit of fluid you have reduced the fluid volume, but the weight is still on top keeping the pressure up (you might lose a bit of pressure because of the loss of fluid weight, but I'm assuming the weight atop the piston is much greater). So taking out fluid doesn't really change the pressure.
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  #7  
Old 11-20-2002, 01:32 PM
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Yes, you're right. The cardio vascular system does have feedback mechanisms to keep the BP at a certain level, such as increasing the heart rate or using vasoconstriction (analogous to your piston example).

I think the key word in the OP is "temporarily". ;-)
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  #8  
Old 11-20-2002, 01:43 PM
Wolverine Wolverine is online now
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I was wondering about this. The following is anectodal evidence from my experience. Two weeks ago I went and had a physical. My diastolic was a little high so they asked to come back in a week and recheck it. During the week I donated blood at Red Cross, 3 days before the appointment. I went back in and my diastolic was down by over 10. Could just be I was more relaxed but donating blood could have helped.
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  #9  
Old 11-20-2002, 02:07 PM
Qadgop the Mercotan Qadgop the Mercotan is offline
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I've seen blood pressures rise after blood donations. This is due to the body's sensing that volume is depleted, and thus tightening vascular tone, heart rate, and cardiac output to compensate, but here overcompensating.
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  #10  
Old 11-20-2002, 02:29 PM
AWB AWB is offline
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Re: Can donating blood reduce high blood pressure?

Quote:
Originally posted by sqweels
Temporarily anyway?
Not if needles give you the heebie-jeebies.
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  #11  
Old 11-20-2002, 03:12 PM
toadspittle toadspittle is offline
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What actually causes high blood pressure, anyway? Never really understood it.
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  #12  
Old 11-20-2002, 04:19 PM
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Quote:
Originally posted by toadspittle
What actually causes high blood pressure, anyway? Never really understood it.
Great question. The truth is, high blood pressure is not really understood that well. Most of the time the cause is unknown. There are a few cases where things like kidney disfunction or narrowing of aortic arteries can cause it, but that is rare.

Generally it's handled with medications that either control the heart rate, dilate vessels or use diuretics to decrease water and sodium in the body.
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  #13  
Old 11-20-2002, 07:28 PM
Qadgop the Mercotan Qadgop the Mercotan is offline
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The most common type of hypertension is "essential hypertension", which means you got it, we don't know why, there doesn't seem to be any other disease causing it. Lose weight, eat less salt, exercise more and you'll do fine. What? You don't want to do that? OK, here, take these drugs for the rest of your life.

Otherwise, less common causes include renal and thyroid disease, along with connective tissue abnormalities, to list 3 out of a thousand causes of "secondary hypertension".
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  #14  
Old 11-20-2002, 07:33 PM
Hari Seldon Hari Seldon is offline
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Well, I know someone who is 5'2", weighs 93lb and has extremely high BP for which there is no known cause. She walks a lot even if she doesn't get much other exercise and is on all the known drugs.
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  #15  
Old 11-20-2002, 08:20 PM
Qadgop the Mercotan Qadgop the Mercotan is offline
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True, Hari. I shouldn't generalize. There are quite a few fit people with essential hypertension. However, they will generally benefit from salt restriction.
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  #16  
Old 11-20-2002, 09:04 PM
don't ask don't ask is offline
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Quote:
Originally posted by gigi


Here is some suggestion of a link between donating blood and reduced risk of heart disease, but it includes the idea that donors may live more healthy lives overall.
Other research in 1999 offered an explanation of the mechanism behind the reduction in health risks.
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  #17  
Old 11-20-2002, 09:14 PM
JillGat JillGat is offline
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The Straight Dope: Does donating blood treat heart disease?
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  #18  
Old 11-20-2002, 09:16 PM
JillGat JillGat is offline
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Not the actual title of the SD column, but anyway.
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  #19  
Old 11-26-2002, 06:28 AM
partly_warmer partly_warmer is offline
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Quote:
Originally posted by Qadgop the Mercotan
The most common type of hypertension is "essential hypertension", which means you got it, we don't know why, there doesn't seem to be any other disease causing it. Lose weight, eat less salt, exercise more and you'll do fine. What? You don't want to do that? OK, here, take these drugs for the rest of your life.
A quantity of perfumed blessings to your enviorns, Qadgop. I've been waiting, indefinitely stalled, to hear such a clear statement of the current recommended practice about this, and hearing little but "Be Good". Nice to hear that other people can't figure it out, either. Ta.
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  #20  
Old 11-26-2002, 07:49 AM
istara istara is offline
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Can someone here please give me the one-line idiot's guide to the difference between systolic and diastolic?
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  #21  
Old 11-26-2002, 10:54 AM
Demo Demo is offline
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Quote:
Originally posted by istara
Can someone here please give me the one-line idiot's guide to the difference between systolic and diastolic?
Systolic pressure is pressure during a heart contraction. Diastolic is pressure during relaxation.
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  #22  
Old 11-26-2002, 02:08 PM
Qadgop the Mercotan Qadgop the Mercotan is offline
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Quote:
Originally posted by partly_warmer
A quantity of perfumed blessings to your enviorns, Qadgop. I've been waiting, indefinitely stalled, to hear such a clear statement of the current recommended practice about this, and hearing little but "Be Good". Nice to hear that other people can't figure it out, either. Ta.
I should add that many hypertensive patients do all the correct things and still require anywhere from one to four different medications to correct their blood pressure. I did not mean to imply that lifestyle modification would automatically make all the difference.
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  #23  
Old 11-26-2002, 02:27 PM
reprise reprise is offline
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I'm not even going to try to attempt a technical explanation for this - I'll leave that to the physicians in residence - but I have chronically low blood pressure. I'm not unhealthy because of it, I just have a tendency to faint in hot weather if I don't drink fluids by the clock.

Twice in my life I have had accidents which involve massive bleeding. Because of the adrenaline the body pumps when you are losing large volumes of blood, my blood pressure actually ROSE while I was losing significant amounts of blood. Had it not been for the ambos who were aware of my chronic hypotension, I would probably have died - there wasn't a single doctor in the ER who realised that I was in trouble once my BP reached 120/80 (that is BIGTIME high for me, and definitely a sign of adrenaline in response to massive blood loss).

Your blood pressure most certainly CAN go down when you donate blood, but for most people the difference in blood pressure is negligible.

I've learned to live with hot weather and the inevitable hypovolemic episodes it brings. I really can't imagine that anyone would WANT to feel the way I feel when my blood pressure does the sudden plummet, let alone allow someone to stick a huge gauge needle in their arm in order to induce that feeling.

I know that QtM is probably going to ask - the worst hypovolemic episode I've had was 90/42, and I was just fine once I had a drink of fluids. Summer and me just don't agree with each other.
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  #24  
Old 11-26-2002, 03:23 PM
sqweels sqweels is offline
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Thanx for the responses. Naturally, the conditions keeping my BP high now would bring it right back up, but I was thinking that if I'm gonna start a regimen designed to lower it, a little bloodletting might be a good way to get the ball rolling.
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  #25  
Old 11-26-2002, 04:15 PM
Spoke Spoke is offline
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Would it be a leap to speculate that we perhaps evolved to bleed a lot more than we actually do these days?

(Our cushy office jobs can't match the African savannah for blooodletting incidents.)
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  #26  
Old 11-26-2002, 04:17 PM
Spoke Spoke is offline
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(Paper cuts notwithstanding.)
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  #27  
Old 11-26-2002, 04:56 PM
reprise reprise is offline
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I don't know about the rules in the US, but here the Red Cross won't accept a donation unless it's been 60 days or more since you last donated. There are certain medical conditions which require regular blood-letting, but if you had one of them you would most certainly know about it.

If you want to donate blood - cool; do it because it's something nice you can do for this world. Just don't do it hoping that it will have a significant impact on your BP, because that impact will be very short-lived.
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