Traditional anti-doping testing looks for a prohibited substance or its metabolites in a sample. The Athlete Biological Passport, or ABP, adds another approach: it monitors selected biological markers over time and looks for changes that are unusual for that individual athlete.
The passport is not a physical document and it does not contain every medical test. It is a secure longitudinal record used by authorised anti-doping organisations and expert panels.
Why monitor changes instead of only substances?
Some prohibited substances disappear quickly, are used in small doses or are difficult to distinguish through one isolated measurement. Their effects on the body can last longer than the substance itself remains detectable.
By establishing an athlete's personal range, anti-doping authorities can identify patterns that deserve closer review. A value that looks normal in the general population may still be unusual compared with the athlete's own history.
The approach complements direct detection; it does not replace ordinary urine and blood testing.
The haematological module
The haematological module examines blood variables connected with oxygen transport and red-blood-cell production. It is particularly relevant to methods intended to increase endurance, including blood manipulation.
Markers can include haemoglobin concentration and reticulocyte-related measurements. The system analyses their relationship across multiple samples rather than declaring a violation from one high or low result alone.
Altitude exposure, illness, dehydration and training can affect blood values, so contextual information matters.
The steroidal module
The steroidal module tracks selected steroid markers in urine. It can help identify unusual patterns associated with the use of anabolic agents.
Because natural steroid profiles differ between people, longitudinal monitoring can be more informative than one universal threshold. An atypical pattern may lead to targeted analysis, including more specific laboratory procedures.
Medication, health conditions and sample quality still require expert consideration.
How the adaptive model works
The ABP uses an adaptive statistical model. Early samples help establish an expected individual profile. As more valid samples are added, the model updates the limits within which future values are expected to fall.
An outlying result creates an atypical passport finding, not an automatic guilty verdict. The model indicates that the pattern has a low probability of occurring under the expected physiological conditions.
The case must then follow review procedures designed to consider legitimate explanations.
Who reviews an abnormal profile?
Athlete Passport Management Units and qualified experts evaluate passport data. They review sample timing, analytical quality, competition schedule, altitude, illness and other relevant factors.
If experts conclude that a prohibited method is a likely explanation and the case meets the required standard, the anti-doping organisation can proceed under the applicable rules. The athlete must receive notice and an opportunity to respond.
Independent and consistent expert review is essential because biological data can be complex.
Can the passport lead to targeted testing?
Yes. One of the passport's most important uses is intelligence-led testing. A suspicious change can prompt authorities to collect additional blood or urine samples at a strategically useful time.
The extra test may directly detect a prohibited substance, strengthen the longitudinal record or reveal a normal explanation.
Targeted testing makes anti-doping programmes less dependent on purely random selection.
Is an abnormal value proof of doping?
No. Exercise, travel, altitude, infection, blood loss, medical treatment and natural variation can affect markers. A single abnormal laboratory value is not equivalent to an anti-doping rule violation.
The passport process examines the complete profile, sample integrity and possible explanations. Cases must follow the World Anti-Doping Code and relevant international standards.
Public reporting should therefore distinguish an atypical finding, a provisional suspension and a final violation decision.
Sample collection and chain of custody
Samples are collected under controlled procedures, sealed and transported to an accredited laboratory. Documentation records the sample identity while protecting the athlete's personal information.
Timing matters. Training load, recent competition, altitude and other conditions may be recorded because they help experts interpret the result.
Failures in collection, transport or analysis can affect whether data are valid for passport purposes.
Does every athlete have a passport?
Anti-doping organisations decide which athletes and sports to include based on risk assessment, resources and testing plans. Endurance disciplines have historically received significant haematological monitoring, but passport programmes extend across many sports.
An athlete may have samples in the anti-doping system without every possible module being actively used in the same way.
The term should not be used to imply that all competitors undergo identical schedules.
Privacy and medical data
Passport information is sensitive personal data. Access is restricted within the anti-doping system and governed by data-protection standards.
Authorities need the information to administer testing and cases, but they must limit use, retention and disclosure to legitimate anti-doping purposes. Premature leaks can harm athletes before a profile has been fully reviewed.
Why the ABP matters beyond sanctions
Longitudinal data can deter doping because athletes know manipulation may leave a pattern even when a specific substance is no longer present.
It also improves how testing resources are used. Rather than collecting identical samples at predictable times, organisations can respond to individual profiles and sport-specific risks.
The passport works best as one part of a wider programme including education, investigations, whistleblower information and laboratory research.
The bottom line
The Athlete Biological Passport monitors selected biological markers over time. Unusual patterns can trigger expert review and targeted testing, and in properly supported cases may contribute to an anti-doping proceeding. It is a structured evidence process, not a one-number guilt test.
For more rules and analysis from across global sport, browse the latest guides in our Sports section.
Source: World Anti-Doping Agency Athlete Biological Passport operating guidelines and the World Anti-Doping Code.
