What Steps Need To Be Taken With The Following Blood Test Result?

I have recently been diagnosed with ITP (Last week). I am also a Ulcerative colitis patient since 2013. My platelets are 18k. I take Mesalamine for UC control. I have had blood tests which display normal results other than platelet count being low and mild anisocytosis.I have been prescribed 2 weeks of Prednisolone 60mg. I am reluctant to take it because it may help in the short term, but I don t like the idea of the side effects and the inevitable relapse after tapering.I wanted to know if I should have other diagnostic tests, as my liver and bone marrow hasn t been tested?