Victoria's Deputy Premier Peter Ryan is "itching to get back into action" as he undergoes hospital tests to diagnose a possible blood infection, Premier Ted Baillieu says.

Mr Ryan has been absent from state parliament this week as he undergoes tests in hospital for what could be a blood infection.

Premier Ted Baillieu said his deputy remained in good spirits.

"Apart from feeling a bit flat I think he's not too bad," Mr Baillieu told reporters in Melbourne.

"He's just been advised to stay in hospital while they conduct some tests and he's been working from a hospital room but we decided yesterday we'd take the workload off him and give that to some other ministers while he completes those tests.

"But he's still chirpy and positive and itching to get back into action."

It is not known how long Mr Ryan will be absent but his diary has been cleared until Tuesday.