Khloe Kardashian and Lamar Odom arrive at The 2011 Teen Choice Awards ceremony in the Universal City, California in this 2011, July 8 file photo. [Photo/IC]

Khloe Kardashian, whose whirlwind romance with Odom was captured in "Keeping Up With the Kardashians" and its spin-off, "Khloe and Lamar," was at his bedside, TMZ and Us Weekly reported.

The couple split in 2013 after four years of marriage and their divorce was finalized in July, though she has remained in close contact with him.

Khloe's half-sister, model Kendall Jenner, posted a tweet on Wednesday saying "please don't go," that was believed to refer to Odom.

Odom publicist Eve Sarkisyan said in a statement that "family and friends are extremely concerned for Lamar" but warned against "false information being circulated unofficially."

Odom's hospitalization followed a downturn in a 14-season career with National Basketball Association teams, including the Lakers from 2004-2011.

Besides the pressures of the life of a top NBA player, Odom, whose mother died when he was 12, had to deal with being a reality TV star after marrying Kardashian.

The 6-foot, 10-inch-tall (2-metre) athlete has long been reported to have had issues with cocaine abuse, although this has never been publicly confirmed. He has admitted only to using marijuana.

During the 2000-2001 season, Odom was suspended for violating the NBA's antidrug policy. In 2013, he pleaded no contest in Los Angeles to a charge of driving under the influence and was ordered to undergo rehabilitation for three months for alcohol abuse.