North Melbourne's star AFL midfielder Daniel Wells has experienced blood clots on the lungs and has been placed on blood-thinning medication.

The All-Australian nominee has been ruled out of North's pre-season training camp in Utah but club officials are hopeful the 26-year-old will be fit for round one in 2012.

"Wells has suffered a major setback following post-season shoulder surgery," the Kangaroos said in a statement on Saturday.

"Daniel was discharged from The Avenue hospital after the operation and experienced chest pain, lower back pain and shortness of breath and advised club medical staff. He was immediately re-admitted to hospital for tests.

"Specialists discovered a large blood clot in Daniel's lungs and further tests were conducted."

Wells has been cleared of any abnormalities or disorders, the club said.

"However, Daniel will be placed on a blood-thinning drug for next six months and will not be able to travel with the team to Utah for its high-performance training camp in October," the Kangaroos said.

"He will also be unable to participate in any training drills which involve contact but can maintain and improve his fitness with a view to playing close to the beginning of the 2012 season."

Wells was named earlier this week in the All-Australian squad of 40.

The 22-man team will be announced on September 19.

Brought to you by AAP © 2024 AAP