With a fever, a medical checkup blood draw can have an effect. Fever is often seen in the case of viral and bacterial infections, and there will be a marked elevation of white blood cells, and there may also be a marked elevation of neutrophils. In the case of viral infections, there will be a marked increase in lymphocytes. In addition, in the fever, the blood in the body is more concentrated state, hemoglobin will appear high phenomenon. During fever, the body tends to carry out a certain inflammatory reaction, so, at this time to draw blood for testing of C-reactive protein, often manifested as high. C-reactive protein is a kind of acute-phase inflammation protein, when there is inflammation in the body, the C-reactive protein will be manifested as a phenomenon of elevation. It has no effect on other tests, such as blood sugar and blood lipids.