's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

So how high can the hematocrit go?(12 posts)

So how high can the hematocrit go?Eug
May 24, 2003 4:37 AM
Just wondering. Apparently some doc said Pantani showed up in emerg once with a hematocrit of 60. If true, he must have been pretty dehydrated then but it's well known he was EPOing or blood doping, giving him quite a head start. I think he was at 52 or something when he was kicked out.

I wonder what hematocrit people would have if they could train in the Himalayas? I will note that 8 women living on top of a mountain (Pike's Peak at around 4500 m?) ended up having crits on average of about 49-50. ie. The average natural hematocrit was higher than what road racing allows (for women). Presumably, most of the time they were sitting around inside. The only "drug" they were taking was iron supplements.

Bernardo Guarachi is an insane mountain climber from Bolivia, and has had crits clocked in at 70% (probably with dehydration), with usual hematocrits in the mid-50s (at about 3500 m).

On a personal note: My sedentary non-athletic slightly overweight father had to go to Tibet at one point. At first he could barely walk a block but he said he felt relatively OK by the end of the trip. When he came back to Canada he said was bounding up flights of stairs like a kid, two steps at a time. I think he was only in Tibet a week or so. Most of the time he was the whole time in Lhasa (3700 m), and being the non-athlete, he did not venture out onto higher mountain trails or anything.

I wonder at what hematocrit people start dropping dead. 65%?
re: So how high can the hematocrit go?kevinmd
May 24, 2003 7:39 AM

I may be ranging a bit on the edges of my knowledge of medicine, so bear with me.

For those of us who don't know, 'crit' or hematocrit is the percentage of the blood volume made up of red blood cells. The rest is other blood cells, proteins, electolytes and water. Normal range for men is roughly 39-45% and for women a bit lower. Well trained athletes often have hematocrits that tend to run on the low end of normal. Folks who live at high altitude do not have higher crits than the rest of us, they have other methods of enhancing oxygen delivery.

Why is this so? The limiting factor during exertion is oxygen delivery from the lungs to the peripheral tissues and the removal of waste products. However, oxygen delivery is the major limiting factor. Not enough oxygen? You go anaerobic and start to build up lactate (a waste product of anaerobic metabolism. The two main factors determining delivery are cardiac output and oxygen carrying capacity. Other minor factors are the ability of the tissues to extract the oxygen from the red blood cells, the ability of the muscle to store oxygen (tiny amounts) and the ability of your lungs to ventilate (in healthy people, not an issue).

Oxygen carrying capacity is determined by the amount of hemoglobin in your blood (all hemoglobin is contained in red blood cells) and thus hematocrit is a measurement of your oxygen carrying capacity. Think of the red blood cells as box cars that carry oxygen. The other part is cardiac output, which is determined by stroke volume (how much blood you pump per beat) and rate. So volume x rate gives your cardiac output for one minute. The higher the output, the faster the boxcars move, the more oxygen is delivered to your tissues. Lance Armstrong's stroke volume is much higher than my 'weekend warrior' heart, so at the same rate, he is going to deliver much more oxygen to his tissues. Thus well trained folks with very low heart rates (40s), are moving as much oxygen as I do, but they do it by moving 80cc of blood per beat (for instance) versus my 50cc.

Once your hematocrit gets much above 50%, your blood becomes rather viscous and can have difficulty flowing through the tiny blood vessels in your periperhal tissues. I am not familiar with anyone who naturally has high crits like you described in your note, but they may exist. Folks who live at extreme altitude for their entire life, usually expand their blood volume, increase their absolute number of red blood cells (but not the crit) and have, or develop a variety of biochemical changes that allow their red blood cells to be more efficient and their periperhal tissues better at extracting the oxygen. When you train at altitude, your body makes these changes, but to optomize your oxygen delivery at altitude can take a few months. When you descend, you have better oxygen delivery until your body reverses these changes because the extra blood volume and red blood cells are metabolically expensive (extra iron, extra calories and fluid intake to maintain) and unneeded at lower altitudes. This change also takes a few months. So an athlete who trains at altitude, can have an advantage over a sea level athlete.

If you are getting dehydrated enough to increase your crit to 20% above normal, that means that you have lost 10% of your total body water -- severe dehydration and would be suffering major performance dropoff. Heck, I'm not sure if you could even muster a slow jog at that level of dehydration. For me, I would have to lose 20 pounds of water to become that dehydrated. Ouch. When I see a patient with that level of dehydration (granted, they are not athletes, but older folks) they are damn near on death's door.

I am sure this is as clear as mud, but feel free to fire off questions.

-- Kevin MD
re: So how high can the hematocrit go?268generation
May 24, 2003 9:30 AM
But when the blood becomes more vicous doesnt it also have increased level of RBC (thus more oxyglobin) so won't that actully improve performance ?

Little bit of dehydration = good ?
Im just a student wondering.

Well, after a point it can be TOO viscous.Eug
May 24, 2003 9:48 AM
ie. Obviously a crit of 45 is better than one of 35, but I'd much rather have a crit of 50 than a crit of 60.

I'm just now sure at what point the sequelae of high viscosity (eg. microvascular damage or stroke or whatever) start really to show themselves.
But people at very high altitude have much higher hematocrits.Eug
May 24, 2003 9:44 AM
Thx for the long response, but I believe that this statement is incorrect:

"Folks who live at high altitude do not have higher crits than the rest of us, they have other methods of enhancing oxygen delivery."

While they do have other methods of enhancing oxygen delivery, it is well-documented that hematocrits increase as well. That's why I provided the example of the 8 people working at the top of Pike's Peak for several months. All were women, and the average measured hematocrit was almost 50, which would make most of them ineligible to compete in road bike race. They'd be accused of EPO use or blood doping.


It's about Bolivians living at high altitude and describes a certain "physiologic polycythemia" where as much as 11% of women and 28% of men living in La Paz (3510 m) have hematocrits over 56%. For those living in El Alto (4100 m), the incidence was even higher, at over half of males and over a quarter of females.

Now these data may be biased, because it's a hospital population, and many are likely to have bad pulmonary disease or may be smokers, but nonetheless the values are much higher than those of us living at much lower altitudes.
Addendum and a "FWIW".KG 361
May 26, 2003 7:15 AM
I work in a hospital lab. Any hematocrit that reads above 50 we consider "critical" (worthy of notifying a Dr immediately) so you can take that FWIW.
re: So how high can the hematocrit go?russw19
May 24, 2003 9:48 AM
I have seen race checks before the 50% rule that had riders above 60%. A few years back within a 3 month span 4 Dutch cyclists died, all having hemocrits above 64%. I seriously doubt they tried to boost their levels that high, but think it would be more a combination of the levels being too high compounded by extreme dehydration.

As for Pantani... while I am no fan, nor supporter of the guy, it's a stretch to say it's well known he was doping. The media tells us one thing, but what do we really know? Now you could easily claim it is well suspected, but well known is a stretch. OK enough splitting hairs....

The day Pantani was thrown out of the Giro, he had a valid point on why he should be kept in. They tested his blood less than 5 minutes after the finish of a very tough mountain top finish before he had a chance to drink even one of those little 6 oz. cans of Coke. You could see the salt crusties all over his jersey and face that day, but they still tested him at altitude while dehydrated. He was tested the day before and had a level of 48% and he was tested on the rest day 3 days eariler (to the best of my memory) and was tested at 48% as well.

So this leaves 3 (maybe more) valid scenarios. 1 is that he was not using anything.. he is naturally at around 48%, and the combination of altitude and dehyration caused his hemocrit level to be artifically high.
2. He was on EPO and tried to keep the level at 48% to fall within the range of acceptable.. and the combination of altitude and dehydration boosted his level too high and he got caught.
3. He was doped and doped above the legal limit and got caught. Period.. end of story... altitude and dehydration were not factors and he just pushed the limits too high.

Which ever of those, or if another is really the truth, we will probably never know. But I am convinced that it is either the first or second.. I am willing to bet altitude and dehydration were factors in the test. But by my saying that, I am still not saying if he was or was not clean at the start of the stage, just that if they knew him to be doped, they sure picked a good time to prove it with the tests.

To answer your last question, I am no doctor, and this is what I understand to be true from reseaching this on the net in the past... it is by no means fact, and only my interpretation of what I have read.

It seems to me that what kills riders is the rapid change in the hemocrit level. There isn't a magic number that kills people, but it seems that the body can't handle drastic changes in its hemocrit level. Often the blood for doped people gets so thick it clots and can cause a Pulmonary Embolism in the brain causing a deadly stroke. An interesting fact is that often Corticosteroids are used to treat and prevent these blood clots (I haven't figured out why) but Corticosteroids are often abused in cycling. Maybe the use of them helps prevent problems with EPO use as well... But the point that the blood clots and can form the Pumonary Embolism is not specific, so there really is no magic drop dead number from what I can find.

Anyone else have input on this?

Thx. Didn't realize the whole story, but Pantani had a syringe.Eug
May 24, 2003 10:05 AM
I didn't realize what the whole story was, thx. It does seem like a bad idea to do a hematocrit 5 minutes after the race.

Nonetheless a syringe was found in his room.

I can't assume anything, but your option 2 seems like the most likely story. ie. He was on EPO and finally got caught because of dehydration.
Hmmm... Syringe had insulin. Weird.Eug
May 24, 2003 10:06 AM
This story just gets weirder and weirder...
4 people in the hotel room that night too...russw19
May 24, 2003 10:16 AM
Not saying one way or the other... just that we really don't know because even the facts aren't well known.

I would point at Pantani's lack of form (up until this Giro) as more of proof that he wasn't clean, but then I went thru a depression spell while racing and I could ride for turd during that time.

All I am saying is that we can speculate about Pantani, but we really can not say we know him to have been doped. How thin that arguement happens to be is really funny though, because the same can be said about OJ. Not a single one of us knows for a 100% fact that OJ killed Ron and Nicole, but most of us are pretty sure. The reality is that we weren't there and don't know.

Picture of woman with 67% hematocrit.Eug
May 24, 2003 9:57 AM
Below is a picture of a woman with a 67% hematocrit. Definitely not an athlete on EPO. ;) And she didn't have polycythemia vera either.

And here is her chest X-ray:

She certainly isn't a picture of health, but nonetheless she was able to function relatively normally in everyday life.
re: So how high can the hematocrit go?kevinmd
May 26, 2003 4:08 AM
Alrighty then,

As I said, I was stretching my medical knowledge a bit. I just checked a text on wilderness medicine (by Auerbach, et al for those of you interested) that states that HCT does increase at altitute. So I stand corrected. Usual increase it to right around 50%. In fact, in some folks it can go higher, but that is not thought to be a healthy response and phlebotomy (blood letting) is recommended if the HCT exceeds 60%.

-- Kevin MD