Team Sky has withdrawn Colombian rider Sergio Henao from racing to conduct further tests after its monthly review provoked questions over his blood values.
The 26-year-old, who was born at altitude in Rionegro and lives and trains in the region outside of the racing season will be subject to an "altitude research programme", Team Sky has announced.
Henao has been withdrawn from racing for eight weeks, meaning he is unlikely to start the season's opening Grand Tour, the Giro d'Italia, which begins in Belfast on May 9.
Team Sky principal Sir Dave Brailsford said on teamsky.com: "Our experts had questions about Sergio's out-of-competition control tests at altitude - tests introduced this winter by the anti-doping authorities. We need to understand these readings better.
"We contacted the relevant authorities - the UCI (International Cycling Union) and CADF (Cycling Anti-Doping Foundation) - pointed to these readings and asked whether they could give us any insights.
"We've also taken Sergio out of our race programme whilst we get a better understanding of these profiles and his physiology.
"We want to do the right thing and we want to be fair. It's important not to jump to conclusions."
Team Sky is well aware of the benefits of altitude training - with Tour de France winners Sir Bradley Wiggins and Chris Froome training at altitude to improve performance - but the longer-term effects are not so clear.
Brailsford added: "Our own understanding is limited by a lack of scientific research into 'altitude natives' such as Sergio.
"We are commissioning independent scientific research to better understand the effects of prolonged periods at altitude after returning from sea level, specifically on altitude natives.
"The independent experts are looking to use WADA-accredited laboratories and Team Sky will make the data and findings available to WADA, the UCI and CADF.
"Sergio will help with this programme and we expect him to be out of the race schedule for at least eight weeks. Once we have completed our assessment, we'll decide on the right steps and give a full update."
It is the second blood anomaly Team Sky has been part of.
Jonathan Tiernan-Locke, the 2012 Tour of Britain winner, faces anti-doping disciplinary action after his blood passport data was found to contain anomalies.
His fate is in the hands of the UK Anti-doping Agency.