Amateur scientist wrote:
Could you explain what biochemical processes could lead to a false positive EPO test result in a sample that was inproperly handled and stored? From what I have read about the EPO test I would have thought that improper handling and storage would more likely lead to a false negative rather than a false positive but I am not an expert in this area so I would be interested in your insights.
From a biochemist: ^^^^This^^^^
The false positive rates on these tests are also notoriously low. This is a conscious decision established by the testing agencies so that an absolutely unequivocal level of synthetic EPO to Natural EPO ratio constitutes a positive test, as determined by MALDI-TOF. As a result, the amount of false negatives is around 80% according to Don Caitlin, and false positives are in the low single digits. To offset the low single digits (even 1% isn't an OK number of FPs) they have the B sample. The chances that two tests come back falsely positive is 0.01^2, or 0.0001 (one in ten thousand) which is an acceptable number. However, this means that even if you test positive on your A (only ~1% chance its a mistake) the chances your B is also positive is very low, given the agreed upon cutoff ratio for a positive test. This is what happened to Lagat.
Also, consider that the t(1/2) of EPO is like 1-3 days and the effects are 3-4 months. So you could take it a month before and have new RBCs all in your blood stream without even the slightest trace of EPO. Hence the ideas of blood passports.