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Ask the Doctor, with Dawn Richardson: Hydration and hematocrit
Dear Doc;
Mine isn't the usual write-the-doc-for-advice question. I am mostlyjust curious as to how dehydration affects one's hematocrit. Do red cellsalso lose fluid such that the net impact on hematocrit is minimal?This question is prompted by LanceArmstrong's severe dehydration in the first individual time trial ofthis year's Tour de France. Given the potential reduction in serum volumeassociated with such severe dehydration (6.5 kg), would Lance's hematocrithave exceeded the allowed limit in a post-race test, assuming a normalhematocrit with proper hydration? Was Lance subjected to a post-race testas the leader (I believe that he was leading at the time)?Incidentally, I seem to recall that Marco Pantani used dehydration asan explanation for failing a hematocrit test in the Giro in 1999. Was thata valid explanation?
Todd GanderDear Todd;
Thanks for your question. It does raise an interesting topic. Dehydrationwill, in fact, raise the hematocrit. Intracellular water losses also occurwith dehydration, but the net result is still a temporary relative increasein one's overall hematocrit.The dehydration issue was actually addressed by the UCI when they establishedthe hematocrit monitoring rule in 1997. It was because of the effect ofdehydration that those blood tests are only given in the morning. To myknowledge, post-race testing is limited to urine testing for performance-enhancingdrugs. This includes the urine test for EPO that has been developed inthe last couple of years. It can take more than the 12 hours from the endof a stage to the usual 6:00 a.m. pre-race vampire visit for dehydrationto be corrected with oral and/or intravenous hydration. One could conceivablyhave a hematocrit above 50 percent the day following severe dehydrationif the baseline hematocrit is borderline high. Team doctors should be monitoringthis very closely.The take home message for elite endurance athletes is that you shouldhave an idea of your baseline hematocrit range. I have a minority opinionthat 50 percent is too low a number for the UCI to be using as a cutoff,I think it should be more like 52 percent, the standard high normal hematocritused by many U.S. hospital laboratories for normal adults. There are athleteswho have a high hematocrit waiver from the UCI because they naturally andconsistently run above 50 percent. A failed hematocrit test would be aterrible way to find out you run high naturally. For professionals, theUCI also mandates regular medical check-ups. Hematocrit levels are amongthose things tested in these regular check-ups.Altitude tents are, of course, used by many athletes to raise theirhematocrit levels "naturally," although the use of such a hypobaric chamberis not consider a valid reason for the UCI to grant a medical dispensation.A rider who claims a naturally high hematocrit is required to submit years'worth of medical data to support the claim.Bear in mind that Pantani’s high hematocrit in the 1999 Giro was pre-EPOtest. Despite the mandatory hematocrit test - which was already in placewhen the 1998 Festina scandal struck - one might assume that EPO abusewas rampant at that time.
Dawn Richardson
Dawn Richardson is a board certified emergency medicine physician in practice at Saint Anne’s Hospital in Fall River, Massachusetts. She is frequent contributor to SG: surf snow skate girl magazine, and is interested in health-related issues for cyclists, and women’s health. She welcomes medical questions pertaining to cycling, bearing in mind that if it ain’t emergency medicine she may have to do some work to figure out an answer. Please send your questions or issues to "Ask the Doctor" in care of WebLetters@7Dogs.com.Important Notice:
The information provided in the ASK THE DOCTOR column does not constitute formal medical advice. The information provided on this public web site is provided solely for general interest of the visitors to the site. The information contained in this column applies to general medicalpractice and may not reflect current medical developments or be interpretedas medical advice. Understand that reading the information contained inthis column does not mean that you have established a doctor-patient relationship with Dr. Dawn Richardson. Readers of this column should not act upon any information contained in the Web site without first seeking medical advice from their personal physician.
