WHAT IS A COMPLETE BLOOD COUNT? - MEDICINE - 2024

The CBC, cytometry hematic or blood count, is a detailed study of the measurements and characteristics of the cells present in the blood, especially the size, shape and quantity of each.

It is the study most commonly used by medicine in any of its specialties, since the information obtained places in the hands of the health professional parameters destined not only to obtain an accurate and timely diagnosis, but also the disposition of the organism to respond to proper treatment.

- Red series

Refers to mature and immature erythrocyte cells:

Reticulocytes

Reticulocytes are the most immediate precursors of erythrocytes, that is, it is an immature erythrocyte. It represents approximately 1% of the red series under normal physiological conditions, its size varies from 10 to 15 µ in diameter, it is anucleated, it has RNA, mitochondria and ribosomes, and it is not very flexible.

Erythrocytes

Also called red blood cells. When the reticulocyte matures, after approximately 24 hours, it loses its RNA and becomes an erythrocyte.

It is biconcave, anucleated and extremely flexible, a characteristic that allows it to transport hemoglobin through each capillary, and that facilitates the exchange of oxygen by diffusion as it has a larger surface area. It measures approximately 6 to 8 µm and has a half-life of 120 days.

- White series

It refers to the total number of white blood cells present in the blood.

Leukocytes

They are the nucleated cells responsible for the immune response and represent approximately 1% of the total blood volume. There are 5 types of leukocytes:

• Neutrophils: they are responsible for responding to bacterial or mitotic infections. They have a multilobed nucleus, they engulf bacteria and when they die they form pus. Their half-life is 5 days and they make up approximately 60% of total leukocytes in the blood.
• Basophils: they are responsible for responding to allergens, their nucleus can be bilobed or trilobed. Their half-life is approximately 48 hours, they release histamine and occupy 0.5% of the total leukocytes present in peripheral blood.
• Eosinophils: they are responsible for responding to allergens and parasitic infections, their nucleus is bilobed, their half-life is approximately 6 hours in blood, and they occupy about 2.5% of the total leukocytes.
• Lymphocytes: there are different types of specialized lymphocytes, some called small ones measure 7-8 µ and the so-called big ones measure 12-15 µ. They represent approximately 30% of the total leukocytes in the blood. In short, they respond to viral infections and the presence of tumor cells, produce antibodies, and promote adaptive immunity. Its nucleus is eccentric and its half-life varies from weeks to years according to each type of lymphocyte.
• Monocytes: they migrate to other tissues to become macrophages, they have a kidney-shaped nucleus, they measure 12 to 15 µm, their half-life is approximately 3 days and they occupy 5% of the total leukocytes in peripheral blood.

Platelets

They are small cell fragments, made up only of cytoplasm, without a nucleus. They are also called thrombocytes and their main function is to promote hemostasis, if there is any leakage in the endothelium of a blood vessel, to avoid massive bleeding.

Cell characteristics and reference values

Regarding the red series, the following characteristics are evaluated:

Number of red blood cells per mm

The expected reference values ​​are modified according to sex, 4.5 - 5 million per mm3 are expected for men, and 4 - 4.5 million per mm3 for women.

Hemoglobin

Its values ​​are also dependent on sex, for men it is estimated at 13 - 18 g / dL, and for women 12 - 16 g / dL.

Hematocrit

It is responsible for specifically measuring the solid percentage of the blood, it depends directly on the concentration of red blood cells per mm ³. Normal values: 40 - 50%.

Mean Corpuscular Volume (MCV)

It refers to the average size of each red blood cell. Reference value: 80 - 100 femtoliters (fL). Its measurement reveals the concepts of macrocytic (> 100fL) and microcytic (> 80 fL).

Mean Corpuscular Hemoglobin (HCM)

It measures the amount of hemoglobin per red blood cell. Reference values: 28 - 32 picograms / cell (pg). The concepts of hypochromic (<28 pg), normochromic (28 - 32 pg) and hyperchromic (> 32 pg) emerge from it.

Corpuscular Mean Hemoglobin Concentration (CCMH)

It refers to the concentration of hemoglobin in a group or mass of erythrocytes. Reference values: 32 - 36 g / dL.

Erythrocyte Distribution Width (ADE)

It measures the variation in the size of the red blood cells. Reference values: 11.5 - 14.5%.

Regarding the white series, the complete hematic biometry mainly evaluates the amount of each of its cells present per liter (x10 ⁹ / L), their reference values ​​are the following:

Reference values ​​in the white series

• Leukocytes: 4.5 - 11.5 x10 ⁹ / L
• Neutrophils: 55-70% of leukocytes
• Eosinophils: 1 - 4% of leukocytes
• Basophils: 0.2 - 1.2% of leukocytes
• Monocytes: 2 - 8% of leukocytes
• Lymphocytes: 17 - 30% of leukocytes
• Platelets: 150 - 400 x10 ⁹ / L

References

1. Mayo Clinic. Complete Blood Count. By Mayo Clinic Staff August 09, 2017. Recovered from:.mayoclinic.org
2. com Medical Definition of Erythrocyte. (2016). Recovered from: medicinenet.com
3. Lewis SM, Bain J, Bates I ed. Dacie and lewis: Practical Haematology. 10th ed. Philadelphia: Churchill Livingston Elsevier; 2006.
4. Suárez A. et al. Manuel A Mir of Hematology. 3rd Edition. Spain. (2009)
5. Almaguer-Gaona C. Clinical interpretation of hematic biometry. University Medicine. 2003; 5 (18): 35-40.