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A new study released by researchers in Denmark raises further questions about the effectiveness of the urine test used to detect the presence of the red-blood-cell-boosting drug EPO.
The test has been in use in cycling since 2000 and is currently the detection method regarded as standard in anti-doping laboratories around the world.
In a study published in Thursday’s online edition of the Journal of Applied Physiology, lead author Carsten Lundby, a physiologist at the Copenhagen Muscle Research Center, said that urine samples, known to be positive for EPO, produced inconsistent test results, with many of the samples ultimately classified as negative or “suspicious.”
The test, which attempts to distinguish between natural human erythropoietin and its artificially produced counterpart (rEPO), relies on the fact that the metabolites of the two carry different electrical charges. Despite those differences, however, the distinction is often unclear.
“It’s super-difficult,” Lundby told the New York Times on Thursday. “The difference between the EPO you have in your body and the recombinant EPO is not very great.”
In testing the reliability of the detection method, Lundby said urine samples from a group of eight male test subjects, who were injected with EPO over a four-week period in the summer of 2007, were sent to two different IOC-certified labs. One of the labs never found any of the samples to be positive, while the other was able to consistently identify positive samples when test subjects had recently injected a high dose of EPO.
The second lab, however, was able to find only six of 16 samples of urine collected during a lower-dose “maintenance” phase of injections were positive for signs of rEPO use.
The test was hailed as a milestone in the fight against doping, but was subject to early criticism, since even its developers noted it was effective only within three-to-five days of an injection, while the drug improves performance for three to four weeks.
The test was further criticized because some athletes found the three-to-five day window shrank to a matter of hours, if athletes relied on small, regular, intravenous “micro-doses,” as opposed to the larger, less-frequent doses recommended for anemia patients, for whom the drug was originally developed.