Biological passport

An athlete biological passport is an individual electronic record for professional athletes, in which profiles of biological markers of doping and results of doping tests are collated over a period of time. Doping violations can be detected by noting variances from an athlete’s established levels outside permissible limits, rather than testing for and identifying illegal substances.[1]

Although the terminology athlete passport is recent, the use of biological markers of doping has a long history in anti-doping. Maybe the first marker of doping, that tries to detect a prohibited substance not based on its presence in urine or blood, but through the induced deviations in biological parameters, is the so-called testosterone over epitestosterone ratio (T/E). The T/E has been used by sports authorities since the beginning of the 1980s to detect anabolic steroids in urine samples. A decade later, in 1997, markers of blood doping were introduced by some international federations, such as the Union Cycliste Internationale (UCI) and the Federation Internationale de Ski, to deter the abuse of recombinant erythropoietin that was undetectable by direct means at that time. It is only in 2002 that the concept of using biological markers to detect doping became known by the term athlete passport. The merits of this testing paradigm were exposed in the scientific literature[2] and the terminology adopted by the World Anti-Doping agency.[3]

Many believe[who?] that the athlete passport provides an excellent alternative to ensure fairness in elite sports. While a new drug test must be developed and validated for each new drug, the main advantage of the athlete passport is that it is based on the stability of the physiology of the human being. New drugs are produced at an unprecedented pace today and there is often a lag of several years between the availability of a new drug and the application of an effective detection method. In contrast, the physiology of the human being remains the same through several generations and all biomarkers developed today in the athlete passport will remain valid for at least several decades. For example, the blood module of the passport is already sensitive today to any new future form of recombinant erythropoietin, as well as to any form of gene doping that will enhance oxygen transfer to the muscles. Also, while a negative drug test does not necessarily mean that the athlete did not dope, the athlete can present his/her passport at the beginning of a competition to attest that he/she will compete in his/her natural, unaltered condition.

The athlete passport received a lot of attention when its blood module was established at the beginning of the 2008 racing season by the UCI.[4] In May 2008 they revealed that 23 riders were under suspicion of doping following the first phase of blood tests conducted under the new biological passport.[5]The blood module of the athlete passport aims to detect any form of blood doping, the steroid module any form of doping with anabolic steroid and the endocrine module any modification of the growth hormone/IGF-1 axis. Each of these modules are however at different steps of development, validation and application in sports.

Athlete biological passport testing

According to the World Anti-Doping Agency, the athlete biological passport is administered to establish whether an athlete is manipulating his/her physiological variables without detecting a particular substance or method. The biological passport uses the standardized approach of urine sampling to determine steroid abuse. The objective of this testing is to identify athletes in a haematological module and a steroidal module.

The haematological module tests for certain markers in the body that identify the enhancement of oxygen transport. The specific markers the module tests for include haematocrit, haemoglobin, red blood cell count, percentage of reticulocytes, reticulocytes count, mean corpuscular volume, mean corpuscular haemoglobin, mean red cell distribution width, and immature reticulocyte fraction.

The steroidal module collects information on markers for steroid doping and aims to identify endogenous anabolic androgenic steroids. The specific markers the module tests for include testosterone, epitestosterone, the testosterone/epitestosterone ratio, androsterone, and etiocholanolone.[6]

The World Anti-Doping Agency recently released the 2014 Prohibited Substances list and it will take effect on 1 January. In the new list, the agency modified the definitions of exogenous and endogenous steroids being tested for in the steroidal module of the biological passport.[7]