Nick Cannon reportedly "should have been recovered" from his health issues by now.

The 31-year-old America's Got Talent host was hospitalised last Friday in order to treat blood clots in his lungs and an enlarged ventricle on the right side of his heart.

Nick underwent the treatment while recovering from the mild kidney failure he experienced over the holidays.

The star has had to resign from his post at New York City radio show Rollin' with Nick Cannon on 92.3 NOW to focus on his health.

Friends and family are concerned for Nick's wellbeing.

"He didn't give himself time out of hospital. It was getting worse," a source told People magazine. "Waking up that early in the morning and his travel schedule was gruelling. He should have been recovered at this point."

Nick recognises the gravity of his situation and will do as his medical personnel advises.

"Under doctor's orders, I have been asked to put my health first and cut back on some of my professional commitments in order to allow my body to get the rest that it needs to keep up with the demands of my multi-tasking schedule," Nick released in a statement Friday. "Even Superman has to sleep."

Nick has ten-month-old fraternal twins wife Mariah Carey.