Published online 24 February 2006 | Nature | doi:10.1038/news060220-18


Bad blood

The possible use of illicit substances and practices such as blood doping have hung over this year's Winter Olympics in Turin. takes a look at what has been going on.

What has happened?

Blood doping by transfusions is outlawed at the Olympics.Blood doping by transfusions is outlawed at the Olympics.© Getty

Blood tests of twelve cross-country skiers revealed abnormally high red blood cell counts, leading to 5-day suspensions and causing an uproar in the sports scene as athletes were unable to participate in their events.

Most of these athletes have already been cleared of any doping suspicions by further tests. But regardless the International Olympic Committee (IOC) argues that the suspensions were valid for health reasons: having too high a red blood cell count can potentially lead to dangerous clotting.

A second major incident overshadowed the Games last weekend. In surprise raids by Italian police, syringes, unlabelled drugs and transfusion equipment was found in the Austrian ski team's quarters. The IOC hasn't yet released the results of blood tests on the team.

Why would someone want a high red blood cell count?

Red blood cells contain hemoglobin, which carries oxygen around the body. A higher count of red blood cells leads to a better oxygen-supply to muscles, improving endurance, strength and speed.

How high can the count be?

Normal haemoglobin levels are about 14-17 grams per deciliter of blood in men and 12-15 g/dL in women.

Different sports and competitions have different allowable limits. The International Ski Federation (FIS) accepts a maximum of 17 g/dL hemoglobin in men and 16 g/dL in women. The suspended athletes were all less than a gram above these limits

How can you boost your count?

A high count, called polyglobulia, can be caused by a number of things.

People living or training at high altitude show constantly raised hemoglobin-levels. As a reaction to the low oxygen supply, the kidneys produce more of a small hormone called 'erythropoietin' (EPO), a growth factor for the production of red blood cells in bone marrow. One study of people in the Andes showed natural levels as high as 21 g/dL.

The same thing can happen when other conditions reduce oxygen supply to the organs, including chronic lung- and heart diseases or heavy smoking. A few rare, inheritable genetic disorders can lead to a high red blood cell count. But most of these are accompanied by symptoms that would preclude the person becoming an Olympic athlete. Simple dehydration can also make the blood thicker, indirectly raising red blood cell concentrations.

Or it could be the result of blood doping.

What's that?

Athletes can inject concentrated haemoglobin from themselves or another person using blood transfusion equipment, or take drugs such as synthetic EPO to raise their count.

These activities are banned at the Olympics.

Is it really dangerous to have a high count?

That depends heavily on the individual. Some athletes who have a naturally high count can get an exemption from the normal limits from the IOC.

There is an elevated risk of developing thrombosis from a high red blood cell count, particularly along with dehydration and stress, says Fernando Dimeo, doctor at the Department of Sports Medicine at the Berlin university hospital Charité. "Since you can not tell an athlete to train less, the best way of avoiding too concentrated blood is simply by drinking a lot," says Dimeo.

Some coaches disagree with the IOC's strict limits. "A hemoglobine value of 16.3 %, as Evi Sachenbacher showed for instance, you can by no means call dangerous," says Wilhelm Schänzer, professor and doping expert at the German Sport University in Cologne.

Can you tell if someone has naturally high levels or has been cheating?

Tests for EPO were invented in the late nineties and have been used at the Olympics since the 2000 Summer Games in Sydney.

There is yet no way to tell whether someone transfused his own blood. A quick jump in red blood cell count from one week to the next looks suspicious, however. One potential approach that hasn't yet been put into use would be comparing the ratio of young blood cells to older ones: a transfusion would result in a higher proportion of adult cells.

Are there other reasons why the athletes might have transfusion equipment?

It is allowed for athletes to inject certain complementary substances, including vitamins and electrolytes. And some athletes might be diabetic. But all drugs to be injected should be clearly labelled at an Olympic venue.

What about gene doping?

This is expected to be the next frontier for athletes. Instead of using drugs or fresh blood to pump up the body's production of red blood cells, what if you could modify your genes to do it for you?


Repoxygen, a product of the british company Oxford BioMedica is one of the first products that could officially be classified as gene doping. It uses viral transmission of a vector bearing the human EPO-gene, and can make muscle cells start to produce EPO. Repoxygen was originally created for use by people whose kidneys don't function properly

This drug is still in pre-clinical development and it is thought that no gene doping has yet occurred in sport. But experts say it is just a matter of time.

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