Hemogram – Understand your results

The blood count is one of the most useful and most requested blood tests in medical practice. Although extremely common, this is an examination that still causes a lot of confusion in the population and even in the media.

The blood test does not work like the antivirus on your computer that automatically crawls across the machine looking for something wrong. When the doctor asks for a blood sample, he needs to tell the laboratory what he wants analyzed in this sample. In our blood circulate various substances that can be dosed or researched, such as proteins, antibodies, cells, electrolytes (potassium, sodium, calcium, magnesium, etc.), cholesterol, hormones, drugs and even bacteria or viruses in cases of infection.

If the doctor wants to know how cholesterol levels go, he needs to write in the request that he wants a dosage of cholesterol; If the goal is to know if the blood glucose is controlled, the blood glucose is dosed. A blood count is requested when the objective is to have information about the blood cells, namely, leukocytes, platelets and red blood cells. Therefore, in a blood count, it is not possible to obtain data on cholesterol level, glucose level, bacterial screening, drug screening, HIV test, etc.

In this text we will explain what types of information the blood test can bring us.


See now which are the cells that, by means of the hemogram we can study:

– Blood cells.
– Leukocytes (white blood cells).
– Platelets.

The current reference values of the hemogram were established in the 1960s, after observation of several individuals without diseases. What is considered normal is, in fact, the values that occur in 95{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of the healthy population. 5{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of people without medical problems may have blood count values outside the reference range (2.5{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} slightly below and a further 2.5{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} slightly above). Therefore, small variations for more or less do not necessarily indicate some disease. Obviously, the further away a result is from the reference value, the greater the chance of it truly representing some pathology.

I’m not going to stick to specific values, since labs are currently counting automatically through machines, and benchmarks are always printed in the results. Each laboratory has its own reference value and, in general, they are all very similar.


The erythrogram is the first part of the blood count . It is the study of red blood cells, that is, red blood cells, also called erythrocytes.

Look at this fictitious example below. Remember that reference values may vary between laboratories.

The first three data, red cell count, hemoglobin and hematocrit, are analyzed together. When they are reduced, they indicate anemia, that is, low numbers of red blood cells in the blood. When they are elevated they indicate polycythemia, which is the excess of circulating red blood cells.

The hematocrit is the percentage of blood that is occupied by red blood cells. A hematocrit of 45{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} means that 45{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of the blood is composed of red blood cells. The other 55{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} are basically water and all other substances diluted. It can be noted, therefore, that practically half of the blood is actually composed of red cells.

If on the one hand the lack of red blood cells impairs the transport of oxygen, on the other, red cells in excess leave the blood very thick, disrupting its flow and favoring the formation of clots.

Hemogram values
Example of Hemogram – Part of the erythrogram

The hemoglobin is a molecule that is inside the red cell. It is responsible for the transportation of oxygen. In practice, the hemoglobin dosage ends up being the most accurate in the evaluation of anemia.


The mean globular volume (VGM) or mean corpuscular volume (VCM), measures the size of the red blood cells. A high VCM indicates macrocytic red blood cells, ie, large red blood cells. VCMs indicate microcytic red cells, that is, of decreased size.

This data helps to differentiate the various types of anemia. For example, folic acid deficiency anemia occurs with large red blood cells, whereas iron deficiency anemia occurs with small red blood cells. There are also anemias with normal-size red blood cells.

– ANEMIA FERROPRIVA | Iron deficiency

Alcoholism is a cause of increased VCM (macrocytosis) without anemia.

The MCHC (mean corpuscular hemoglobin concentration) or CHGM (mean corpuscular hemoglobin concentration) evaluates the concentration of hemoglobin within the red cell.

The MCH (mean corpuscular hemoglobin) or HGM (mean corpuscular hemoglobin) is the weight of hemoglobin within erythrocytes.

The two values indicate basically the same thing, the amount of hemoglobin in the red blood cells. When RBCs have few hemoglobins, they are called hypochromic. When they have many, they are hyperchromic.

Like VCM, HCM and CHCM are also used to differentiate the various types of anemia.

The RDW is an index that measures the difference in size between the red blood cells. When it is high, there are many red blood cells of different sizes. This may indicate red cells with problems in their morphology. It is very common for RDW to be elevated, for example, in the iron deficiency, where the lack of this element prevents the formation of normal hemoglobin, leading to the formation of a reduced size red blood cell.

Except for hematocrit and hemoglobin, which are easy to understand, the other erythrogram indices are more complex and people with no medical training will hardly be able to interpret them correctly. You need to know all kinds of anemia well so that this data can be useful.


Leukogram is the part of the blood count that evaluates leukocytes. These are also known as white series or white blood cells. They are the defense cells responsible for fighting invading agents.

Leukocytes are actually a group of different cells, with different functions in the immune system. Some leukocytes directly attack the invader, others produce antibodies and some only identify the invading microorganism.

The normal value of leukocytes ranges from 4000 to 11000 cells per microliter (or cubic millimeters).

There are five types of leukocytes, each with its particularities, namely:

1) Neutrophils

Neutrophil is the most common type of leukocyte. It represents, on average, 45{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} to 75{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of circulating leukocytes. Neutrophils are specialized in fighting bacteria. When there is a bacterial infection, the bone marrow increases its production, causing its blood concentration to rise. Therefore, when we have an increase in the number of total leukocytes, caused basically by the elevation of neutrophils, we are probably facing a bacterial infectious picture.

Neutrophils have a life span of approximately 24-48 hours. Therefore, once the infectious process is controlled, the marrow reduces the production of new cells and their blood levels return rapidly to baseline.

Neutrophilia → is the term used when there is an increase in the number of neutrophils.
Neutropenia → is the term used when there is a reduction in the number of neutrophils.

We explain leukocytosis with neutrophilia in more detail in the article:  WHAT DO LEUCOCYTOSIS AND NEUTROPHILIA MEAN?

2) Segmented and rods

Bats are young neutrophils. When we are infected, the bone marrow rapidly increases the production of leukocytes and eventually launches freshly produced young neutrophils into the bloodstream. The infection must be controlled quickly, so there is no time to wait for these cells to mature before releasing them into combat. In a war the army does not send only its most experienced soldiers, it sends those that are available.

Usually only 4{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} to 5{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of circulating neutrophils are rods. The presence of a higher percentage of young cells is a hint that there may be an ongoing infectious process.

In the medical environment, when the hemogram shows many rods, we call this finding a “deviation to the left”. This denomination derives from the fact that the laboratories list the different types of leukocytes by placing their values side by side. As the sticks are usually on the left in the list, when there is an increase in their number it is said that there is a left shift in the blood count . So if you hear the term deviation on the left, it just means that there is an increase in production of young neutrophils.

Segmented neutrophils are mature neutrophils. When the patient is not sick or is already in the final stage of disease, virtually all neutrophils are segmented, that is, mature cells.

3) Lymphocytes

Lymphocytes are the second most common type of white blood cells. They represent 15 to 45{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of the leukocytes in the blood.

Lymphocytes are the main lines of defense against virus infections and against the onset of tumors. They are also responsible for the production of antibodies.

When we have a viral process in progress, it is common for the number of lymphocytes to increase, sometimes exceeding the number of neutrophils and becoming the most circulating type of leukocyte in circulation.

The lymphocytes are the cells that make the recognition of foreign organisms, initiating the process of activation of the immune system. Lymphocytes are, for example, the cells that initiate the rejection process in organ transplants.

Lymphocytes are also the cells attacked by the HIV virus. This is one of the reasons AIDS (AIDS) causes immunosuppression and lead to opportunistic infections.

Lymphocytosis = is the term used when there is an increase in the number of lymphocytes.
Lymphopenia = is the term used when there is a reduction in the number of lymphocytes.

Note: Atypical lymphocytes are a group of lymphocytes with different morphology, which can be found in the blood. They usually appear in the tables of virus infections, such as mononucleosis, influenza, dengue, chicken pox, etc. In addition to infections, some autoimmune drugs and diseases, such as lupus, rheumatoid arthritis and Guillain-Barré syndrome, may also stimulate the onset of atypical lymphocytes. Attention, atypical lymphocytes have nothing to do with cancer.

4) Monocytes

Monocytes normally account for 3 to 10{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of circulating leukocytes. They are activated in both viral and bacterial processes. When a tissue is being invaded by some germ, the immune system routes the monocytes to the infected site. It activates, transforming itself into a macrophage, a cell capable of “eating” invading microorganisms.


Monocytes typically rise in cases of infections, especially in the more chronic ones, such as tuberculosis.

5) Eosinophils

Eosinophils are the leukocytes responsible for combating parasites and the mechanism of allergy. Only 1 to 5{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of circulating leukocytes are eosinophils.

Increased eosinophils occur in people with allergies, asthma or in cases of intestinal infection by parasites.

Eosinophilia = is the term used when there is an increase in the number of eosinophils.
Eosinopenia = is the term used when there is a reduction in the number of eosinophils.

6) Basophils

Basophils are the least common type of leukocytes in the blood. They represent 0 to 2{b246d8715a49a229bfad551fa6c95ff8dfd676e0f52344f95da00cc3b04a64a4} of the white blood cells. Its elevation usually occurs in allergic processes and states of chronic inflammation.


When leukocytes are increased, we call leukocytosis. When they are diminished we call leucopenia. Leukocytosis can be caused by lymphocytosis or by neutrophilia, for example. Leukopenia may occur due to lymphopenia or neutropenia.

When we notice increases or decreases in leukocyte values, it is important to see which of the six strains described above is responsible for this change. As neutrophils and lymphocytes are the most common types, they are usually responsible for the increase or decrease in leukocyte concentration.


Large elevations can occur in leukemias, which is nothing more than leukocyte cancer. While infectious processes can raise leukocytes to 20,000-30,000 cells / mm3, in leukemia these values easily exceed 50,000 cells / mm3.

Leukopenia usually occurs from lesions in the bone marrow. They can be by chemo, by drugs, by invasion of cancer cells or by invasion by microorganisms.


Platelets are fragments of cells responsible for the start of the coagulation process. When a tissue from any blood vessel is injured, the body quickly routes the platelets to the site of the lesion. Platelets cluster and form a thrombus, a kind of stopper or stopper, which immediately stains the bleeding. Thanks to the action of platelets, the body has time to repair the damaged tissue without much loss of blood.

The platelet normal value ranges from 150,000 to 450,000 per microliter (uL). However, until values close to 50,000, the organism does not present difficulties in initiating the coagulation.

When values are below 10,000 platelets / μL there is a risk of death, as there may be spontaneous bleeding.

Thrombocytopenia is what we call the reduction of blood platelet concentration. Thrombocytosis is the increase.

Platelet dosage is important prior to surgeries and to evaluate bleeding conditions without definite cause.


When we have reduced two of the three blood cell lines, we call it bicytopenia. When all three cell types are reduced, we call it pancytopenia. Diseases that occur with chronic inflammation, such as lupus, for example, may present with a reduction of one, two or three lines. In fact, any aggression to the bone marrow, whether by drugs, infections or diseases, can cause a decrease in the production of blood cells.


It takes no preparation, or fasting, to collect blood for the blood count .

The term complete blood count is only a preciousness, since there is no incomplete blood count . If the doctor only wants to know the value of hematocrit and hemoglobin, he asks for an erythrogram. If you want to see only the value of leukocytes, just ask for a leukogram. If the target is only the platelets, a plaque is required. When a hemogramis requested , it is implied that the doctor wants the evaluation of the three strains (red blood cells, leukocytes and platelets).