Madonna's friends are thought to be worried she "burnt herself out" with an "extremely risky" workout schedule while trying to compete with younger stars like Taylor Swift.
A source has said the singer's friends feared there would be "another Michael Jackson situation" after he died in the run-up to his This Is It tour in 2009.
Madonna, is thought to have been constantly pushing herself in the run up to her Celebration Tour, which her pals think contributed to her hospitalisation.