Athlete Biological Passport and Whereabouts

The Athlete Biological Passport is an electronic record that tracks selected biological markers in an individual athlete over time. Rather than trying to detect a prohibited substance directly, it looks for the effect that doping has on the body, which is why it is called indirect detection. Blood doping, for example, changes the blood in characteristic ways whether or not the drug itself can still be found.

The power of the passport comes from using each athlete as their own reference. Repeated samples, collected over months and years, build a personal profile with an expected range for that individual. An adaptive statistical model flags values that fall outside what would be expected for that person, taking natural variation into account. A flagged profile does not by itself prove doping; it is reviewed by a panel of independent experts who consider whether a medical condition, altitude, illness or another factor could explain it before any conclusion is drawn.

Two features make the passport valuable. It can support an anti-doping rule violation on its own, based on an abnormal profile over time, even without a positive test for a specific substance. It also guides testing, since a suspicious profile can trigger targeted, no-notice testing. In this way the passport both detects and directs, and it rewards consistent monitoring rather than a single lucky catch.

The passport has established haematological and steroidal modules, and World Anti-Doping Agency (WADA) guidance now also includes an endocrine module. The haematological module monitors markers in the blood that reflect the production and turnover of red cells, including the concentration of haemoglobin and the proportion of young red cells, the reticulocytes. Blood doping, whether by transfusion or by drugs that stimulate red cell production such as erythropoietin (EPO), disturbs these markers in ways the passport can detect, since it changes the balance between mature and newly made cells. This module targets methods aimed at boosting the oxygen-carrying capacity of the blood, which is a powerful advantage in endurance sport.

The steroidal module monitors the steroid profile in urine, including the ratio of testosterone to epitestosterone (T/E ratio) and related markers. Using anabolic androgenic steroids, or testosterone itself, shifts this profile away from the athlete's normal pattern, which flags the possibility of steroid use even when a substance identical to the body's own hormones would be hard to detect directly. The endocrine module applies the same longitudinal principle to markers of human growth hormone doping and related endocrine manipulation. Across all modules the principle is the same: watch the athlete's own biology over time and look for the changes that doping produces.

Testing only at competitions would miss a great deal, because many prohibited substances and methods are used in training and timed to clear before an athlete competes. Whereabouts information solves this by allowing no-notice, out-of-competition testing. Athletes in a Registered Testing Pool, the group selected for the most rigorous testing, provide regular information on where they will be, including their overnight address, their training and competition schedule, and a specified sixty-minute slot each day when they can be found at a given location for testing. In UK Anti-Doping (UKAD) terminology, it is athletes in the National Registered Testing Pool who provide this daily sixty-minute slot, while athletes in the Domestic Testing Pool provide whereabouts information but not the slot.

Failing these obligations has consequences. A filing failure occurs when the information is late, incomplete or inaccurate, and a missed test occurs when the athlete is not at the declared location during their slot. For athletes in the National Registered Testing Pool, any combination of three whereabouts failures within a rolling twelve-month period amounts to an anti-doping rule violation, even though no prohibited substance has been found, while for other pools the consequences may differ, so the athlete's exact pool status matters. Whereabouts is demanding, but it is what makes out-of-competition testing, and much of the passport, possible.

The passport is robust partly because it accounts for the things that legitimately move biological markers. Altitude training, iron deficiency or supplementation, recent illness, blood loss and even significant changes in training can all shift the markers the passport follows, which is exactly why flagged profiles are reviewed by experts rather than acted on automatically. Testing standards also specify a waiting period after training or competition before certain blood samples are collected, so recent training, competition, altitude exposure, blood loss and transfusion history all remain important context. For the clinician, this is a reminder that an athlete's blood results sit in a wider context, and that documenting relevant treatment, such as iron therapy or a recent illness, is good practice.

The clinician's role here is mostly one of awareness and integrity. Supporting an athlete means understanding the obligations they carry, helping them stay compliant where appropriate, and being alert to the medical factors that influence the passport. It also means a firm line: a clinician must never assist an athlete to falsify whereabouts, avoid a test, or manipulate a sample, all of which are themselves anti-doping rule violations. Handled well, these systems protect clean athletes, and the clinician supports that by combining good medicine with a clear respect for the rules.

• •The World Anti-Doping Code, the International Standard for Testing and Investigations, and WADA's Athlete Biological Passport operating guidelines together underpin whereabouts, sample collection and the management of the passport.
• •Passport profiles are reviewed by independent expert panels, who weigh medical and physiological explanations before any finding is reached.
• •UK Anti-Doping (UKAD) manages the testing pools and whereabouts obligations for athletes in the United Kingdom and provides guidance on filing through its systems.
• •UK sport and exercise medicine practice expects clinicians to understand anti-doping responsibilities, document medical factors that may affect biological markers, and signpost athletes to UKAD or sport-specific guidance when uncertain.

• •The Athlete Biological Passport uses indirect detection, tracking an athlete's own biological markers over time rather than detecting a substance directly.
• •The haematological module monitors blood markers for blood doping, and the steroidal module monitors the urinary steroid profile for anabolic steroid use.
• •Each athlete acts as their own reference, and flagged profiles are reviewed by independent experts before any conclusion.
• •An abnormal passport can support an anti-doping rule violation without a positive test for a specific substance.
• •Athletes in a Registered Testing Pool must file whereabouts and provide a daily sixty-minute testing slot, enabling no-notice out-of-competition testing.
• •For Registered Testing Pool athletes, three whereabouts failures, meaning missed tests or filing failures, within a rolling twelve-month period amount to an anti-doping rule violation.