Complete blood count in the blood test

Blood tests include the complete blood count with differential blood count (or hemogram), which shows the cell elements in the blood:

  • red blood cells,
  • white blood cells,
  • platelets.

It is not necessary to fasting before a complete blood count, but it is necessary for other blood analyses (especially during blood glucose tests).

The laboratories differ somewhat in the interpretation of the results, so the absolute value of these figures cannot be taken into account.

Here is a list of the positions that the doctor interprets using the reference values:


Number of leukocytes (white blood cells) in the complete blood count

Normal values: from 4 to 10 cells/μl

The white blood cells help fight infections. Therefore, an increase in the number of leukocytes may be useful to detect infection. However, it can also indicate leukemia, which can cause an increase in the number of white blood cells.
On the other hand, the lack of white blood cells can be caused by certain medications or diseases.

What leads to a low leukocyte count?

  • Diseases of the bone marrow
  • Chemotherapy
  • Autoimmune diseases
  • Virus infections

What leads to an increased leukocyte count?

Differential blood count

The differential blood count indicates the cellular composition of the white blood cells (leukocytes) of the blood.

Normal reference values:

  • Neutrophils 40% to 60% of total
  • Lymphocytes 20% to 40%
  • Monocytes 2% to 8%
  • Eosinophils 1% to 4%
  • Basophils 0.5% to 1%

This study measures:

  • Number
  • Form
  • Size.

The differentiated leukocyte count also shows whether the number of different cells is in the right proportion to each other.
An abnormality in this investigation could indicate that:

  • Infection
  • Inflammation
  • Autoimmune disease
  • anemia,
  • other diseases.

Decreased neutrophil levels in the complete blood count

Neutrophils are the most numerous white blood cells in the blood.
These cells have the task of protecting the body from infections.

Causes of low neutrophil counts

Ethnic group
Some ethnic groups have a lower number of neutrophils than average:

  • African
  • African American
  • Yemenite Jews
  • Jordanian Arabs

Congenital neutropenia

  • Cyclic neutropenia
  • Severe congenital neutropenia or Kostmann syndrome

Blood and bone marrow diseases

Medicines and toxic substances

  • Chemotherapy
  • Antibiotics and diuretics
  • Alcohol
  • Radiotherapy
  • Insecticide

Causes of infection

Organ changes

  • Enlargement of the spleen, a premature destruction of blood cells in the spleen

Autoimmune diseases

  • Hyperthyroidism (Graves’ disease)
  • Lupus
  • Rheumatoid arthritis

Nutrient deficiencies

  • Vitamin deficiency (B12)
  • Folic acid
  • Copper

Symptoms of severe neutropenia (< 500 neutrophils per microliter)

Typical symptoms and diseases that occur in patients with severe neutropenia are:

  1. Fever
  2. Pneumonia
  3. Sinusitis (sinusitis))
  4. Middle ear infection (otitis media)
  5. Inflammation of the gums (gingivitis)
  6. Inflammation of the navel (omphalitis)
  7. Skin abscesses

Severe congenital neutropenia may be accompanied by severe symptoms.

Elevated neutrophil levels
An increase in neutrophil count may be caused by:

  1. Acute infection
  2. Acute stress
  3. Eclampsia
  4. Gout
  5. Myeloid leukemia
  6. Rheumatic fever
  7. Thyroid inflammation (thyroiditis)
  8. Trauma
  9. Pregnancy
  10. Menstruation
  11. Tissue damage or tissue necrosis:

Number of erythrocytes (red blood cells)

Normal values: from 4.2 to 5.9 million/μl
There are millions of red blood cells in the body. This test measures the number of red blood cells in a certain amount of blood. This value:

  • helps determine the total number of red blood cells,
  • gives an idea of their lifespan,
  • says nothing about where the problems come from.

If there are abnormalities, the doctor prescribes other examinations.

What does the red blood cell count mean?
The red blood cells bind the oxygen from the blood and transport it to the tissues of the entire body.
Normal results

  • Men: 4.7-6.1 million/μl
  • Women: 4.0-5.4 million/μl

Why is the number of red blood cells lowered?

  • Lack of iron
  • Lack of vitamin B12 or folic acid
  • Anemia due to insufficient production of red blood cells due to bone marrow disorders
  • Hemolytic anemia
  • Blood loss due to wounds, internal injuries or heavy menstrual flow
  • Chemotherapy

Why is the number of red blood cells increased?

  • Dehydration
  • Kidney problems
  • congenital heart disease
  • Lung disorder (emphysema, COPD)
  • Altitude
  • Smoke

Values of hematocrit (HCT) in blood analysis

Normal values:

  • 42% to 52% for men
  • 37 to 48% for women

Hematocrit is the ratio between:

  • Volume of red blood cells (erythrocytes)
  • and volume of blood plasma

What is the hematocrit?
This examination is used to diagnose anemia and determine what proportion of the total volume of blood in the body is formed by red blood cells (the percentage of red blood cells in the blood).

Causes of decreased and elevated hematocrit The causes of low hematocrit
are the same as high red blood cell levels and are listed in the previous paragraph.

A high hematocrit can also occur as a result of doping, known as erythropoietin (EPO), a substance found in the human body that stimulates the production of red blood cells.

Values of hemoglobin (Hb) in the complete blood count

Normal values:

  • 14-18 g/dl for men
  • 12-16 g/dl for women

The red blood cells contain hemoglobin, which gives the blood its strong red color. More importantly, the hemoglobin carries the oxygen from the lungs throughout the body and then carries the carbon dioxide to the lungs, where it is exhaled.
Hemoglobin levels vary by sex in healthy people. Low hemoglobin levels may indicate anemia.

What is hemoglobin?
It is a colored substance that carries the oxygen in the red blood cells.

What does decreased or increased hemoglobin mean?
The disorders that lead to low hemoglobin levels are the same as those cited as causes of low red blood cell levels.

Mean single red blood cell volume (MCV) in the complete blood count

Normal values: from 82 to 97 femtoliters
This examination measures the mean volume of red blood cells, or the average amount of space occupied by each red blood cell.
An anomaly could indicate that:

What does the MCV mean?
This value indicates the average size of red blood cells.

What does a lowered MCV mean?

  • Iron deficiency
  • Hemolytic anemia
  • Aplastic anemia
  • Anemia caused by renal insufficiency
  • Chronic diseases

What does increased MCV mean?

  • Lack of vitamin B12 or folic acid
  • Myelodysplastic syndrome
  • Aplastic anemia

Mean corpuscular haemoglobin (MCH)

Normal values: 27-31 picograms

What does the MCH mean?
This test measures the mean amount of hemoglobin in the red blood cell. Very high results could indicate anemia, while too low levels may indicate a nutritional deficiency.

What does a lowered MCH mean?
Iron deficiency

What does an increased MCH mean?
As for the average cell volume of red blood cells, there may also be a lack of vitamin B12 or folic acid.

Mean corpuscular haemoglobin concentration (MCHC)
Normal values: 32-36%
The examination of MCHC refers to the mean concentration of hemoglobin in a certain number of red blood cells. The concentration measures the ratio between the weight of hemoglobin and the volume of the red blood cell in which it is contained.
This value indicates anemia if the number is low, or dehydration if the number is high.

Erythrocyte distribution width (EVB)
Normal values: 11.5-15.5%
If the percentage is high, it means that the majority of red blood cells are of different sizes.
If the value is low, it means that most red blood cells are the same size.
A high EVB value is a possible indication of:

  • Lack of iron, vitamin B12 or folic acid
  • Autoimmune hemolytic anemia or sickle cell anemia
  • Chemotherapy
  • Chronic liver disease

Number of platelets in the blood count

Normal values: from 150,000 to 400,000 ml
Platelets are small blood components that serve to clot the blood.
Too many or too few platelets can affect clotting in several ways.
The number of platelets may also indicate disease.

What does platelet count mean?
Platelets are cells that serve to block skin injuries and prevent blood loss.

What do low platelet counts (thrombocytopenia) mean?

What do high platelet counts mean?

  • Leukaemia
  • Myeloproliferative diseases (resulting in abnormal growth of blood cells in the bone marrow)
  • Chronic inflammatory diseases of the intestine (Crohn’s disease)

Mean platelet volume (MTV)
Normal values: from 7.4 to 10.4 femtoliters
This examination measures the average size of platelets.

A higher value means that platelets are larger, which is a risk factor for:

  • Heart attack
  • Stroke.

A lower value indicates smaller platelets and means that the patient is at risk of bleeding.

BKS values in the complete blood count

BKS, or erythrocyte sedimentation rate, is an examination of the blood that can reveal inflammation in the body.
A BKS examination alone does not bring much, but can serve the doctor to diagnose an inflammatory disease or to follow its course.

When the blood is taken, it is filled into a high and narrow pipette, the red blood cells (erythrocytes) gradually sink to the bottom.
UCS is the unit of the rate at which red blood cells drop.
Inflammation can cause an accumulation of red blood cells, which sink very quickly.

Normal values (Westergren method):

  • Men under 50 years: less than 15 mm/h
  • Men over 50 years of age: less than 20 mm/h
  • Women under 50 years: less than 20 mm/h
  • Women over 50 years of age: less than 30 mm/h


  • Newborns: 0 to 2 mm/h
  • Infants up to puberty: 3 to 13 mm/h

An elevated UCS may be present in:

  • Anaemia
  • Tumors such as lymphoma or multiple myeloma
  • Kidney disease
  • Pregnancy
  • Thyroid disorders

The most common autoimmune diseases include:

  1. Lupus erythematosus
  2. Rheumatoid arthritis in adults and children

A greatly increased BKS can occur in diseases such as:

  1. Allergic vasculitis
  2. Giant cell arteritis
  3. Hyperfibrinogenemia (increased fibrinogen in the blood)
  4. Primary macroglobulinaemia
  5. Necrotizing vasculitis
  6. Polymyalgia rheumatica

High BKS can occur with some infections, including:

  1. Systemic infections
  2. Bone infections
  3. Infection of the heart (endocarditis) or heart valves
  4. Rheumatic fever
  5. Tuberculosis
  6. Encephalitis

Peripheral blood smears Peripheral smears can also be performed during blood analyses
, an examination that provides information about the number and shape of blood cells.
They are carried out to rule out possible abnormalities of red blood cells and platelets regarding:

  • Size
  • Form
  • Structure.

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