Rob Kardashian has reportedly offered to donate one of his kidneys to his brother-in-law Lamar Odom.

A source told DailyMail.com: "Rob is willing to do whatever it takes to help Lamar recover. If that means donating a kidney then so be it, Rob has a big heart and he's willing to step up to help his friend."

However, the former reality TV star still needs to undergo tests to determine whether he and Lamar are a match.

The former NBA star, who suffered multiple strokes and is said to be battling with aspiration pneumonia, is currently undergoing six hours of dialysis - a process to remove waste and excess water from the blood and is used primarily as an artificial replacement for lost kidney function - a day.

However, doctors at Cedars-Sinai Medical Centre in Los Angeles have warned his friends and family that he'll probably need a transplant because his "kidneys are shot."

Meanwhile, Lamar - who was found unconscious in a brothel in Las Vegas, Nevada - is desperate to get better for the sake of his estranged wife Khloé Kardashian, 31.

The 'Keeping Up With the Kardashians' star - the older sister of Rob - rushed to her beau's bedside at Sunrise hospital in Nevada after she learned of his critical condition.

Khloé, who had the athlete moved to a hospital in Los Angeles, has rarely left Lamar's bedside since his collapse and has vowed to support her estranged husband every step of the way throughout his treatment and recovery.

The blonde beauty, who filed for divorce from Lamar last December following four years of marriage, has also dropped proceedings to legally dissolve their marriage.