Quantcast

Tourniquet time may affect doping test results

June 19, 2006

By Anne Harding

NEW YORK (Reuters Health) – The amount of time a tourniquet
is left on an athlete’s arm during blood drawing can influence
hemoglobin and hematocrit levels, both of which are used to
screen for blood doping.

The hematocrit is the percentage of whole blood that is
made up of red blood cells. A value of 42% to 52% in men and
35% to 47% in women is usually considered normal. The normal
amount of hemoglobin — the oxygen-carrying component of blood
– ranges from 13 to 18 grams per deciliter in men and from 12
to 16 grams per deciliter in women.

The new findings confirm that an extended tourniquet time
may result in false-positive doping tests for some athletes,
Dr. Giuseppe Lippi of the Universita degli Studi di Verona in
Italy told Reuters Health.

“An athlete displaying a borderline value of hematocrit
(i.e. 48%) or hemoglobin (i.e. 17.4) … may test falsely
positive during an anti-doping control due to such a
pre-analytical pitfall,” he explained in an e-mail.

Some athletes use drugs — or even transfusions — to pump
up the number of red blood cells they have in their bodies,
resulting in better aerobic performance. Several sport
federations, including the World Anti-Doping Agency (WADA),
have developed testing procedures to identify athletes who may
have been illegally enhancing their red blood cell levels.

Athletes currently undergo blood tests to check their
hematocrit and hemoglobin levels to screen for blood doping. If
they are above a certain cutoff, the athlete may be suspended,
but increasingly athletes with high levels are being checked
with a second, more sensitive blood test.

To evaluate how the procedure used to draw blood might
influence hemoglobin and hematocrit levels, Lippi and his team
analyzed two blood samples taken from each of 27 professional
cyclists. The first sample was taken immediately after the
tourniquet was applied, and the other was taken after the
tourniquet had been in place for an average of 2.3 minutes
(during which time eight more samples were taken for other
blood tests).

The researchers found that the hematocrit measurement
increased 2.4 percent between the first and last samples, and
the hemoglobin level increased 1.4 percent. In 4 of the 27
subjects, hematocrit results varied by 4.1 percent.

This degree of variation could easily push a borderline
athlete into false-positive territory, Lippi said.

Up to 70 percent in the variation of test results for
doping is due to procedural issues such as tourniquet holding
time, he added. Agencies can reduce this variability, and the
risk of false-positive tests, by adopting strict protocols for
collecting blood samples, he added.

If the test administrator does not check for such sources
of variability, Lippi said, “the athlete may potentially be at
the serious risk of being misjudged as a ‘false-positive’.”

SOURCE: International Journal of Sports Medicine, May 2006.


Source: reuters



comments powered by Disqus