The need to understand a person’s health status and the propriety of monitoring their recovery from a major illness, an operation, or fitness for a major kind of treatment such as cancer chemotherapy are some of the reasons why this important test is often requested by doctors. It is, therefore, an important tool in the hands of doctors who are conducting routine health checks on an individual but also in taking control of a particular kind of treatment to help determine a patient’s response to it.
The range of treatments is as wide as you can imagine, and in situations where a person is suffering from profoundly serious infections such as sepsis, this test can even be conducted on a daily basis. By definition, this test is actually many different tests in one cocktail being that it usually measures all the different components of the blood and even establishes how they relate to one another. That is another useful component in the steps necessary to making an eventual diagnosis of a person’s condition. It is also important in the prognostication of a disease condition.
The complete blood count is also called the full blood count and it measures a person’s overall health condition. It can also help in diagnosing simple conditions such as anaemia. In the main, it measures three main components of the blood. These are, namely, the red blood cells, which are the cells of the body responsible for carrying oxygen to the tissues. The CBC or FBC, as the case may be, measures the proportion of red blood cells to the other cellular components of the blood. This specific subset of the blood is called the haematocrit. It is often expressed as a percentage which is more commonly known as the packed cell volume or PCV. This test is also responsible for the determination of how many red blood cells a person has and this aspect is often called the red blood cell count. As this part of the puzzle usually holds some cues for the attending physician, it is not a feature that many people are familiar with as they more usually just confine themselves to knowing what the PCV is. The red blood cells are also of value when their physical characteristics are studied such as their size, and volume. The number of young red cells can also be determined. Finally, in this test, you can also determine the haemoglobin concentration, which is the amount of that protein molecule expressed as a percentage.
The average lifespan of a red blood cell is 120 days which is why in newborns, the mother’s blood continues to be found circulating in the baby during the first three months of life. The red blood cell is produced in the bone marrow which is typically found in the long bones of the body, namely the femur, tibia, humerus, radius, ulna, and fibula. After being produced in all these sites, it is released into the bloodstream where it mixes up with the other components of the blood as we shall soon see. Red blood cells are typically shaped like discs with a dimple at the centre. When there are red blood cell abnormalities such as in sickle cell anaemia, the red cells are seen to look like a half-moon, like a sickle. Such abnormalities can adversely affect the production of red blood cells. Conditions like the HbSS, therefore, can affect that red cell production. This may sometimes be the first indication a doctor will have that something is wrong with the blood of their patient. The bone marrow must, therefore, be able to produce red blood cells at a rate considered sufficient to replace the old ones which are killed after being trapped in the spleen and the liver. Enough must also be produced to replace what is lost from bleeding.
The second part of the blood that is examined under the canopy of the complete blood count is the white blood cell. These cells are also produced in the bone marrow. The white blood cells have different fractions and they form a part of the immune system primed to help the body fight off infections. Around 90 per cent of all these white blood cells are stored in the bone marrow after production where they remain until they are needed by the body when an infection appears. These segments of the white blood cell population that have specific characteristics and functions are called Neutrophils, Basophils, Eosinophils, and Monocytes. A rise in the total white cell count often indicates that there is an infection or an allergic condition. The different types of white cells can respond in unique ways to different conditions such that when there is an increase in neutrophils, it would usually be so when there is a bacterial infection. The basophils typically show an increased presence after an allergic reaction while eosinophils are usually seen after a person is invaded by parasites. The monocytes, which make up between two and eight per cent of the white cell count are seen when an infection becomes chronic.
The CBC or FBC will also estimate the platelet count and the average platelet volume. Platelets have a short lifespan of about 10 days and they are small blood cells that are typically produced in large numbers when a person has sustained some damage and repairs are needed. This damage may be from injury, sickness, or an operation, and these cells are made to ensure that abnormal or prolonged bleeding is prevented in any person. They do this by producing small blood clots that help a great deal in preventing such bleeding. Certain conditions can cause low platelet counts such as an infection.
The more severe the infection, the more the likelihood of this complication and it can be sudden and profound that the blood will just flow out of the body like water from a tap, absolutely without the ability to form clots and limit the loss. Similar conditions can be seen in certain cancers and in perforated gastric ulcers. In the most dramatic scenes, it can be seen in the labour room following a normal vaginal delivery or after a caesarean section. To have a high platelet count is to be confronted with the opposite: certain types of cancer can also increase the platelet count with the risk of more clot formation.
Sometimes, the complete blood count helps to determine whether certain consistencies seen in a particular blood cell are replicated in the others. If, for example, the red blood cells are seen to be persistently low in number, and there is a higher proportion than usual of the presence of young, immature red cells, it may be worthwhile to examine the white cells and the platelets. A similarly uniform reduction in numbers would indicate that there is a primary problem arising from the bone marrow. It would be a serious condition to find a situation in which the bone marrow has become so sick that the production of red and white blood cells is adversely affected and that of the platelets as well. The complete blood count is a simple blood test that measures many things and can help monitor the body’s response to treatment, disease, and adversity. It can also hold profound possibilities for an individual when the figures are wrong and the outlook is dire. It can therefore be seen that it is a simple test with major consequences for the health of the individual and for the outlook of their condition