Abstract: The present invention relates to methods for analyzing at least one blood parameter in a whole blood sample of a patient, wherein the in vitro hemolysis of a whole blood sample is determined. The present invention also relates to a corresponding analysis apparatus, a system for analysing a whole blood sample and a computer program element for controlling the analysis apparatus as well as a computer readable medium storing the computer program element. A method is provided for differentiating the contributions from in-vivo hemolysis and in-vitro hemolysis of an overall hemolysis level determined for the whole blood sample. Blood parameters like potassium or lactate dehydrogenase can then be corrected for hemolytic interference factors.