How does anti-doping testing work for athletes? Inside UCLA's Olympic Analytical Laboratory

UCLA's Olympic Analytical Laboratory (OAL) is one of only two World Anti-Doping Agency (WADA)-accredited drug-testing labs in the United States, and one of 30 worldwide. Founded in 1982 and based in Los Angeles, OAL tests athlete samples for the International Olympic Committee, NCAA, NFL and MLB, screening for hundreds of substances banned under the WADA Code - and it helped perform testing during the 2026 World Cup.

OAL is part of UCLA's Department of Pathology and Laboratory Medicine. Its 35 scientists and data analysts run about 45,000 tests a year using specialized equipment, including 16 mass spectrometers that detect molecules in urine samples.

"There's a lot of science behind this, and that science is important to keep sports fair for everybody."

- Dr. Sarah Dry, chair, UCLA Department of Pathology and Laboratory Medicine

How do labs screen for performance-enhancing drugs?

Labs like OAL analyze urine samples for several categories of banned substances and methods:

• Steroids and muscle-building agents
• Peptide hormones and growth factors
• Diuretics
• Beta-2 agonists (which dilate the lungs' airways)
• Hormone and metabolic modulators (which optimize cell function and energy production)
• Gene and cell doping, and blood manipulation

The list has grown sharply. According to OAL director Elizabeth Ahrens, testing once covered around 100 substances; today, counting parent compounds and their metabolites, the lab screens for nearly 1,000.

"When I first started, we were looking for let's say 100 substances ... now we're talking about - parent substances and metabolites - we're approaching probably 1,000."

- Elizabeth Ahrens, OAL laboratory director

How are athletes tested for banned substances?

Under the World Anti-Doping Code, athletes can be tested at any time - in or out of competition - without advance notice.

The process, step by step:

• A doping control officer notifies the athlete and observes them continuously until testing concludes, per U.S. Anti-Doping Agency (USADA) protocol.
• The athlete provides two 90-milliliter (~3 oz.) urine samples: one for initial testing, one held for follow-up testing if results are adverse.
• The athlete inspects and seals the sample vessel themselves.
• Samples are shipped to OAL or another WADA-certified lab, coded only with a numeric ID - lab staff never know which athlete or team a sample came from.
• Samples are held in temperature-controlled storage until testing begins.
• If a result comes back positive, the athlete may be present for retesting of the second sample.

What are the most popular performance-enhancing drugs?

Steroids remain the most commonly detected performance-enhancing drugs, according to Ahrens, prized for boosting both strength and recovery. Testosterone and its derivatives are most common, alongside anabolic agents like clenbuterol, a bronchodilator with muscle-building and fat-burning effects.

Other frequently detected substances:

Read more about UCLA's OAL Lab at this link.