“Red, orange, yellow, green, blue, purple”, to the hospital to draw blood to sit down, a row of horizontal placed in front of us, the blood drawn is one tube after another, why do you need so many color tubes, less tubes can not? Why do we need so many tubes of blood? The reason for drawing so many kinds of blood is that different indicators require different chemical reagents for testing, and there are different requirements for the blood specimens used, some of which require whole blood, serum, and plasma. Therefore, it is necessary to draw multiple tubes of blood to test. Therefore, the indicators that cannot be tested together should be drawn separately, which is the various “red, orange, green, green, blue and purple” that you see. In fact, the different colors of blood collection tubes you see are to meet the requirements of the specimens of different laboratory tests, the role of different, some add anticoagulants, some add procoagulants, and some do not contain any additives in the blood collection tubes. In order to distinguish the use of blood collection tubes, the international use of different color caps to mark, for example: Why draw so much blood? Why draw so much blood when you are already sick!