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Can someone clarify hematocrit levels for me please?(12 posts)

Can someone clarify hematocrit levels for me please?Sprint-Nick
Oct 24, 2003 3:47 PM
Can someone explain to me why a high hematocrit level deems riders unsafe to race? And is it partially due to the deaths in the past from hearts stopping due to EPO use?

How do two athletes with an elevated hemacrotic level but one has a note and the other does not differ other than the UCI deeming them fit to race? Also do other sports have this check?

Thanks for the clarification.
hematocrit (nm)Sprint-Nick
Oct 24, 2003 3:52 PM
re: Can someone clarify hematocrit levels for me please?lithiapark
Oct 24, 2003 7:11 PM
Sprint-Nick, I don't have answers to all of your questions but I can offer this:
1) hematocrit is measured by drawing blood, letting it clot, and gently centrifuging, and measuring the level of the clot in the tube vs total level of the fluid, and expressing as a percentage, ie: hematocrit of 50% would have blood clot, which contain the blood cells and their oxygen-carrying hemoglobin as well as some clotting proteins, that was 1/2 of the total volume. There are many ways a lab can do this but this is the basic idea.
2) hematocrits more than 50% are uncomon unless a person has severe chronic lung disease or smokes a lot or both-these folk would not be able to deliver enough oxygen to their tissues with normal hematocrits (36-46 or so)so their bodies adapt with higher hematocrits to try and get enough oxygen out of the lungs despite poor lung function. Many heavy smokers with chronic obstructive pulmonary disease have hematocrits of 55-60. Other bone marrow diseases such as polychthemia rubra vera, can produce enough red blod cells that hematocrits over 60 are common.

3)hematocrits more than 50 can rise to 60 or more with dehydration-same amount of red blood cells in the blood, but a lot less fluid.

4)blood with hematocrit above 55-60 begins to flow poorly through capillaries (the smallest blood vessels, not much larger than the diameter of a red blood cell, 8 microns+/-). If too much sludging takes place tissues can starve for oxygen, which in the case of brain tissue results in stroke, or in the heart a heart attack or failure of the hearts pacemaker apparatus.

5) EPO, erythropoetin, is a hormone that causes the bone marrow to produce red blood cells. In and of itself, I don't think it is toxic, it is just that your high hematocrit can be dangerous in a situation where severe dehydration can be dangerous.

6) A very few people have hematocrits above 50% in a completely normal state or with altitude training. I don't know all the ins and outs of the UCI rules and how they allow for this.

I hope this answers some of your questions. My apologies to any hematologists out there or others with great expertise in this area. If my ideas are incorrect, please correct me, I'd be happy to learn more.
Thanks! But just a general EPO questionSprint-Nick
Oct 24, 2003 10:22 PM
Thanks for the insight. Your post did a great job of explaining things.

However, I am left with one last general question. I saw somewhere EPO is flushed out of your system in 3 days but other drugs to prevent blood clots are the markers for its use. Is this true? And if one were to just take EPO would it result in a higher hematocrit level with no positive blood test?

Thanks again,
Thanks! But just a general EPO questionlithiapark
Oct 25, 2003 2:23 AM
EPO should be gone from the body in 3 days and I don't think there are residual break down products of EPO that are specific enough that it could be detected, EPO is normally in the blood so unless the levels were really high, I don't know how you could tell natural from unnatural EPO (it is made from recombinant DNA so it should be pretty much identical to natural erythropoetin, someone correct me if I'm wront). Taking any of the anticlotting medications that could protect against this problem would be a pretty convincing argument that you knew your hct was too high. You would have to take them every day, so they would be easily detected. For a one day race you could stop the EPO a week before, have a high hematocrit through the race, but the EPO would not, I think, be detectable. In a 3 week race you would have to take EPO during the three weeks to keep your hematocrit up where you started, and the higher levels would probably be detectable. Hematocrit levels are easily (in minutes with simple equipment)checked. The results are irrrefutable. It would be pretty much impossible to avoid detection in the long run, in my opinion. There may be some "subhuman mutants" who can train vigourously and naturally raise their hct levels, I'm not sure how the agencies can deal with that. i also don't know how they could deal with a person who has a hct of 48 normally, but gets dehydrated and has a 52 the day they are checked. There is this "close to abnormal range" where a non-EPO user could get caught I think, and this would be very unfortunate.
I'm almost illegal with a 49.2 !OffTheBack
Oct 25, 2003 5:10 AM
First, thanks to lithiapark for a very informed and detailed response. Nice job!

Anyway, I got a whole bunch of blood tests done recently and among them was hematocrit, which came back at 49.2. I live & train at sea level (and don't smoke or take EPO), so it seems like even a slight dehydration would put me into banned territory. Seems a bit arbitrary...
Jeanson couldn't start with >47%...TFerguson
Oct 25, 2003 7:22 AM
is it different for women? Typo?

Its correctSprint-Nick
Oct 25, 2003 8:41 AM
Thats what led me to enquire about all this. Since women have hearts that aren't as big or as strong the limit is lower for them.

Jeanson couldn't start with >47%...lithiapark
Oct 25, 2003 8:47 AM
Females in the general population usually have hct levels 2-3 points lower in averages of large numbers. I don't know how elite female athletes compare. The UCI has a website that lists a lot of info, but I have never found exactly what their limits are, has anyone out there seen where they have published this information? It would seem that a regimen of periodic, not random, testing of hct and EPO would be a better way of dealing with the natural variation among humans rather than an arbitrary limit. In physiology and medicine, "normal" usually means two standard deviations on either side of the mean for a specific parameter such as hct. This encompasses 95% of the individuals. The 2.5% that are above or below two standard deviations from the mean are "statistically abnormal" but are biologically just at the extremes of what mother nature is capable of. It may well be that many elite endurance athletes will fall into this statistically abnormal region which shouldn't be a surprise, they are statistically abnormal in their performance capacity.
Very good pointSprint-Nick
Oct 25, 2003 10:08 AM
This allowance for deviation would eliminate the problems of 2 male athletes both with a hematocrit level of 51% to race when:
1) with a certificate to show he has a naturally high hematocrit level of 51%.
2) dehydrated but has a natural level of 49%.
This natural deviation would effectively put a limit on how dehydrated an athlete would be allowed to become in relation to his hematocrit level. The only problem is how to effectively calculate the baseline...

re: EPO testingcyclopathic
Oct 27, 2003 9:57 AM
there's apparently a test which can determine difference btw EPO and non-EPO red blood cells.
Pretty good info, but a few things...amflyer
Oct 26, 2003 7:01 PM
For hematocrit levels, the blood isn't allowed to clot, and is collected in a tube with EDTA, an anticoagulant used for hemotological studies. The fibrin which forms the bulk of the clot would throw the results way off. Truth be told, nowadays HCT values are calculated from other measured values (red cell count and mean corpuscular volume, if anyone cares) and is not directly measured itself.

Also, statistical values for normal populations show the upper range for male HCT's as 52%. I was never sure how the UCI could penalize at a cutoff that was within normal values.