A method of evaluating a patient's hematocrit includes collecting a sample of blood in a capillary tube, and placing the capillary tube into a centrifuge having a rotor. The centrifuge has base with a center axis and a manual rotation member. The rotor spins in response to the manual rotation member being pulled by an operator, and the rotor is coupled for rotation to the base. The rotor including a plurality of microfluidic channels. The sample of blood is separated with the centrifuge into a red blood cell portion and a plasma portion in the microfluidic channels. A diagnosis image is provided including a base line indicia, a lower normal line indicia, an upper normal line indicia and a 100 % level line indicia. The capillary tube is placed against the diagnosis image with the bottom end placed adjacent the base line indicia.