Lomu was diagnosed with Nephrotic Syndrome in 1996

The Kiwi giant has been forced to take at least a month's break from rugby after a recurrence of his chronic kidney problem.

All Blacks doctor John Mayhew admitted Lomu's career was on the line.

"Since it was first diagnosed we have been walking a tightrope," Mayhew said.

"I am not confident he will play again but I am hopeful. There have been times before when I thought that was it but he has always bounced back.

"Jonah is not a well man and it could be that he has to go on dialysis and receive a kidney transplant. That could happen in a month, a year or never."

Knowing Jonah's fierce determination, I am sure he will be in Australia in October Lomu's manager Phil Kingsley-Jones

Lomu, 27, has been receiving regular treatment since being diagnosed with Nephrotic Syndrome, a rare and serious kidney disorder, at the end of 1996.

He returned from the Welllington Hurricanes' recent Super 12 matches in South Africa feeling very tired, after which medics diagnosed a return of the condition.

"I am always dismayed when Jonah is criticised for his performances because he plays in a state in which most of us would find it hard to go for a run round the block," Mayhew added.

What causes kidney problems?

Lomu will never fully recover from his kidney complaint, and Mayhew will supervise modifications to his treatment over the next four weeks.

He is likely to miss the rest of the Super 12 series, but his manager Phil Kingsley-Jones believes the player will battle back to feature in October's World Cup.

"The car is running short of petrol so we have to put some more petrol in him," Kingsley-Jones said. "Jonah is obviously disappointed about this.

"He is a remarkable person and people should realise just how great his achievements have been, given the handicap he has been living with.

"He made his name in the 1995 World Cup and, knowing Jonah's fierce determination, I am sure he will be in Australia in October."