Spencer Pratt's stint on U.S. reality TV show I'm a celebrity... GET ME OUT OF HERE! has been thrown into jeopardy, after he failed a medical exam.
Show bosses sent The Hills star to a Los Angeles hospital for further tests, after discovering problems with his blood.
On Thursday (21May09) Pratt wrote on his Twitter.com blog, "The doctor just woke me up with a call saying I need to go to the hospital because the test I took show signs of low blood platelets!"
Pratt is preparing to head into the Costa Rica jungle for the endurance show, alongside wife Heidi Montag, Britney Spears' ex Kevin Federline, Stephen Baldwin, Janice DICkinson and Lou Diamond Phillips.