idiopathic thrombocytopenic purpura http://www.itpfoundation.org/itpdefined.htm immune thrombocytopenia acute ITP http://www.itpfoundation.org/itpdefined.htm http://www.itpfoundation.org/itpdefined.htm www.itpfoundation.org www.itpfoundation.org acute ITP www.itpfoundation.org