What Is A Blood Count? What Is It For?

What is a blood count? It is a type of medical analysis by which the number, proportion, and shape of different blood cells can be determined. It is a common diagnostic technique for many diseases.

In this article we explain what this test consists of and what is its usefulness. We also detail the three main cellular elements of the blood that are distinguished in this analysis: red blood cells, white blood cells and platelets.

What is a blood count?

The blood count is one of the most widely used diagnostic techniques in medicine. The reason for its wide use is that with this simple test, carried out on a small volume of blood taken from the patient, much information can be obtained about the state and functioning of the organism.

A blood count consists, above all, of a count of blood elements. Its realization can be demanded by a doctor, if a disorder is suspected or can be carried out routinely, to know the state of health of a person.

With this simple test , multiple pathologies can be diagnosed, ranging from anemia (deficit of red blood cells) to leukemia (excessive proliferation of leukocytes). In addition, a complete blood count can diagnose a variety of viral or bacterial infections.

What is seen in a blood count?

After performing a complete blood count, from a sample of peripheral (venous) blood from a patient, we can observe the levels and shape of the three main cellular elements of the blood : red blood cells, white blood cells and platelets.

Red blood cells or red blood cells

Red blood cells, erythrocytes or red blood cells, are the most abundant blood cells. They have a flattened, disk-shaped shape and are visualized under the microscope as two concentric circles.

Red blood cells are the cells in charge of transporting oxygen to the different tissues of the body. Also to remove the carbon dioxide produced by their cells. Inside it is hemoglobin, a molecule capable of capturing oxygen and carbon dioxide.

Normal levels of red blood cells vary between 4 and 6 million per milliliter. The existence of low levels of red blood cells may imply the presence of bleeding, causing anemia. We can also find low values ​​of red blood cells during menstruation.

On the contrary, high levels of red blood cells usually reflect a deficit in the uptake of oxygen by the body’s tissues. However, the body compensates for it by generating more red blood cells.

Sometimes the cause of this increase is unknown or is associated with a malfunction of the bone marrow. This organ is involved in the formation of red blood cells.

Leukocytes or white blood cells

Leukocytes or white blood cells make up the body’s immune system. They are involved in the defense of the body against infections or external agents. There are several types: lymphocytes, neutrophils, monocytes, eosinophils, and basophils.

Normal levels of leukocytes in the blood range from 4,000 to 10,000 per milliliter. When the levels of this cellular fraction are low (leukopenia), there is a problem in the body’s defenses that can be due to various reasons.

Some infections, such as measles, flu, or HIV, can cause a decrease in the number of white blood cells in the blood. In the same way, this phenomenon can imply a failure in the bone marrow, or ultimately it can be due to the existence of leukemia.

On the other hand, high levels of white blood cells (leukocytosis)  may indicate the existence of a viral or bacterial infection, which has caused the proliferation of immune cells in the body. Allergies or inflammations can also cause an increase in this cell group. This is very involved in this type of process.

Platelets

Platelets are the smallest blood elements. They are actually cell fragments that are unevenly shaped and are involved in blood clotting. Its main function is therefore tamponade and coagulation when there is a wound that can cause loss of blood volume.

Normal platelet levels range from 150,000 to 400,000 per square millimeter. When these levels drop, what is known as thrombocytopenia occurs. This phenomenon may be due to an abnormal accumulation of the same in the spleen, a malfunction of the bone marrow or the existence of some type of autoimmune disease.

On the contrary, the increase in the number of platelets may not have a specific cause.  Again, it can imply certain spinal conditions or the existence of certain diseases or bleeding.

Now we know what a blood count is, as well as the different types of cells that are analyzed. It would be convenient to carry out this type of analysis periodically.