Complete blood count is by far the most ordered blood investigations by physicians and for good reason. The test is cheap, easy to perform and minimally invasive. It can also exclude or confirm a wide range of diagnoses and can be a useful screening tool for many other common disorders which can be used as a starting point to do other more invasive tests for those who need them. Understanding some values in a blood test should be common knowledge since they should be done on a routine basis and understanding the meaning of some results is considered a common knowledge in some societies.
Red blood corpuscles
Our blood is the perfect transportation medium. It is fluid, moves in elastic pipes we call vessels and can coagulate when needed to plug holes in this pipe system as they form. The most important function of blood is the transportation of oxygen which is essential for all energy production in our cells. This function is so essential that some tissues in our body can die if deprived of oxygen for as little as 4 minutes (nerve cells). This function is possible thanks to red blood cells. The term “red blood cells” is actually a misnomer since they are not technically “cells” for they lack nuclei, so they are termed corpuscles, but the name “cells” persists for historical context.
Red blood corpuscles are the most predominant in our blood followed by white blood cells then platelets. They transport oxygen inspired by the lungs through a network of capillaries surrounding the lung alveoli (air sacs). Oxygen is carried on a protein called hemoglobin within red cells. Hemoglobin is formed of 2 portions, the heme which is an iron containing compound and the globin which is a protein. Each hemoglobin molecule can bind four oxygen molecules.