Reanalysis of Samples

Hannah Gribble, Science Officer at UK Anti-Doping explains the importance of storing samples so that they can be retrospectively tested when advancements in scientific technologies occur.

1.  Why would an Anti-Doping Organisation (ADO) want to store a sample?

An ADO may store athlete samples in order to maximise the potential to detect prohibited substances and to achieve greater deterrence for athletes beyond the original time of testing. A strategy for how long to keep samples and when to reanalyse them is important for an ADO to adopt as it enables stored samples to undergo further analysis when new intelligence becomes apparent, new analytical methodologies are introduced, or if the sample was not subjected to a particular type of analysis when initially analysed.

The detection of a prohibited substance when reanalysing stored samples carries the same consequences as committing any Anti-Doping Rule Violation (ADRV) – a ban and loss of any medals.

2.  How long can WADA Accredited Laboratories store samples for?

Under the 2015 World Anti-Doping Code, samples can be stored for up to 10 years.

3.  Can both blood and urine samples be stored and retrospectively analysed?

Yes, both urine and blood samples can be stored and considered for reanalysis.

4.  What substances can be found in reanalysed samples?

The same substances which were prohibited at the time of sample collection.

5.  How many times can one sample be analysed?

In the case of urine, athletes are required to produce a minimum of 90 millilitres when they give a sample, which is split into two bottles the A and B sample, 30ml in the B sample and the remainder in the A sample. This volume allows anti-doping laboratories to conduct a range of tests on a wide variety of substances that are prohibited in sport. The volume remaining following this original analysis of the sample will determine how many times a stored sample can be reanalysed in the future.

When choosing to reanalyse a sample, it is important to consider the volume of urine or blood remaining in the A sample, as there must be enough urine or blood to rescreen the sample to identify the presence of a prohibited substance and then verify these results so that an athlete is not falsely accused of doping.

Additionally, repeatedly freezing and thawing the sample may cause it to degrade, limiting the possibility to reanalyse it again in the future.

6.  If a sample has been stored for 10 years can you still detect prohibited substances in it?

Yes. This has been proven recently where the reanalysis of samples collected from the 2008 and 2012 Olympics has resulted in Anti-Doping Rule Violations (ADRVs).

7.  How can you be sure these samples have been kept in the right conditions for 10 years?

All WADA Accredited Laboratories must adhere to the International Standards for Laboratories that ensure that all samples are stored appropriately. Security is very important in laboratories as well, with access limited to only authorised individuals. In addition, a chain of custody log is maintained throughout the life of a sample. Although unlikely, if anything were to happen to the A sample during its analysis or reanalysis, then laboratories always have a securely sealed B sample also kept in storage.


The ability for an anti-doping organisation to store and reanalyse samples is a very important tool as it acts as a higher deterrent for athletes as they can receive an ADRV up to 10 years after giving a sample. As an anti-doping organisation we protect clean sport and clean athletes. Clean athletes are the ones that miss out on the medal, standing on the podium, hearing their national anthem, prize money and the sponsorship deals that can come with success in sport.

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