Astana rider Lars Boom will race at the Tour de France despite returning blood tests that showed a low level of cortisol.

The Dutchman's tests on July 2 could have forced Astana to rest him for the Tour in line with guidelines set out by the Movement for Credible Cycling (MPCC) – of which the Kazakh team are a voluntary member.

Astana looked to replace Boom - who will play a key part in Vincenzo Nibali's title hopes - ahead of the grand depart in Utrecht on Saturday, however that request was rejected due to the rider facing no health risks.

In a statement the team said: "Team medical staff have advised that Boom's low cortisol result is the consequence of a long-standing and well-known application of anti-asthma therapy by the athlete and is not a violation of UCI rules and regulations.

"Team medical staff have advised that there is no danger to the rider's health or safety to start the 2015 Tour de France.

"Astana Pro Team medical staff will continue to monitor Boom to assess any potential health risk for the athlete, and will retest the athlete in the next days."

Meanwhile, Boom told Dutch television he was surprised to hear any problems with his participation in the 21-stage race.

"I didn't expect it," he told NOS. "I've been using a puffer for my asthma for 10 years and I was sick after the Dauphine.

"I do not have to worry, because I know there is nothing to worry about.

"I've always been 100 per cent against doping, and nothing has changed."