Canadian authorities said on Monday they will perform an autopsy including toxicology tests to determine the cause of death of actor Cory Monteith, the 31-year-old heartthrob of Fox's musical-comedy television series "Glee" who was found dead on Saturday in a Vancouver hotel room.

The British Columbia Coroners Service said the autopsy will be carried out immediately but results will not be available for several days. Toxicology tests are used to determine if drugs, alcohol or other substances were in his body at the time of death.

"We do understand there's a lot of public interest in this case and we will try to get it done in as good a time as we can without compromising the integrity of the investigation," said Barbara McLintock, a spokeswoman for the Coroners Service.

Monteith was found dead shortly after noon on Saturday in his room at the Fairmont Pacific Rim hotel. Vancouver police said they believe he was alone in the room after returning to the hotel early on Saturday morning.

Monteith was public about his struggles with substance abuse. In April, he completed voluntary treatment for unspecified substance addiction at a rehab facility. He had also been treated in a facility at age 19.

The actor, who grew up in Victoria, British Columbia, told Parade magazine in 2011 that he had a serious drug problem during his teenage years for which he received treatment.

Monteith began his career in a number of small roles leading up to a recurring part between 2006 and 2007 in the ABC Family science-fiction drama "Kyle XY" and another role around the same time on the MTV series "Kaya."

"Glee," a show set in the small town of Lima, Ohio, was Monteith's breakthrough. The show is centered on a high school glee club. Popular for its song and dance routines and big-name guest stars, the show has won Golden Globe and Peabody awards.

Monteith played high school athlete Finn Hudson in the series.

For a waning 'Glee,' actor's death poses difficult challenge

The death of "Glee" actor Cory Monteith over the weekend comes just weeks before production begins of the fifth season of the Fox musical comedy, throwing it into disarray at a time when the creators needed to revive the waning series.

Canadian actor Monteith, 31, was not only a founding cast member, but also an integral player in promoting "Glee's" overarching message of tolerance.

Making matters more complicated for producers was his off-screen relationship with another of the show's top actresses, Lea Michele, who plays his love interest on the show.

It is unclear how their story would have proceeded in season five. And in the wake of Monteith's death in a Vancouver hotel on Saturday, representatives at Fox Broadcasting, a unit of Twenty-First Century Fox, were not commenting on the future plans of the show which was scheduled to return to production later this month.

The show was renewed by Fox for two more seasons earlier this year, running through 2015. But producers for "Glee," which has been one of Fox's top shows, were facing some tough truths even before Monteith's death.

"Glee" garnered an average 10.1 million viewers according to Nielsen during its peak in 2010, but its viewership has been dwindling. Season 4, which concluded in May, dropped to the show's lowest ratings average yet, with 8.7 million viewers.

"The show's been running out of storylines and sort of reaching its end thematically ... and Cory's death is a huge loss for the show as one of the founding characters," said Ian Drew, entertainment director of Us Weekly.

Fans want 'Happy Ending'

Monteith had talked openly about his struggles with substance abuse. In April, he completed voluntary treatment at a rehab facility for an unspecified substance addiction.

An autopsy was conducted on Monday and results will not be available for several days.

"Glee" premiered in 2009 and instantly became a hit for Fox, with its motivational storylines, upbeat musical numbers and a diverse young cast playing a mix of popular and oddball school students who come together in a musical choir group.

Monteith became a heart-throb in his role as the jock who turned into "Glee" member Finn Hudson.

"He was actually the center of the show in terms of promoting tolerance," said TV critic David Bianculli. "When his character began, he was the jock that just happened to sing. He ended up liking the misfits and loving them and sticking up for them and eventually teaching them."

MTV Buzzworthy editor Tamar Anitai, who monitors social media buzz on pop culture topics, said "Glee" fans known as "Gleeks" were eager to see a tribute paid to Monteith in the show and a happy ending for his and Michele's characters.

"Unfortunately you can't control what happened to Cory in real life, but the creators have control over what happens to him in the show. Fans would really like to see a happy ending, even an off-screen wedding, for Cory and Lea," Anitai said.

While "Glee" has not shied away from handling serious topics such as homosexuality, bullying and teenage pregnancy, the show never had to deal with the death of a major character. The only death in the show was the sister of Sue Sylvester, the high school coach played by actress Jane Lynch.

Previously when television shows have dealt with the death of a major star, the impact on the series has been mixed.

Actor John Ritter died mid-way through production of the ABC sitcom "8 Simple Rules" in 2003. The show went into a hiatus and then incorporated the death of Ritter's character on its return. Its ratings declined and it was canceled in 2005.

Other major stars to pass away mid-series include Phil Hartman in "News Radio," Nicholas Colasanto in "Cheers" and Larry Hagman in the recently revived "Dallas." All those characters were written out of the shows and new characters replaced Hartman and Colasanto.

While Monteith's death is unlikely to force the early cancellation of "Glee," both Bianculli and Drew said it could mean an eventual end to the series.

"It could be harbinger of things to come, but honestly I don't think the show had much longer anyways," Drew said.