What is a CBC, what is it for and normal values?

A hemogram it consists of a blood test that, in a routine way, is carried out with the purpose of evaluating the general state of health of the person to whom it is done, providing the possibility for the medical specialist to detect different health problems, as for example it is the case of a medical condition or a disease. For example, it is useful for detecting anemia or infections, among many other diseases.

In addition, it is extremely useful to know if a certain organ (for example the kidneys or liver) are working properly, and offers the possibility in turn to discover the total number of different types of blood cells, such as the following:

  • Red blood cells: essential when distributing oxygen to different parts of our body.
  • White blood cells: help fight infections and are a fundamental part of our immune system.
  • Hemoglobin: it is a protein belonging to the red blood cells that carries oxygen.
  • Hematocrit: it consists of the proportion of red blood cells in comparison with the plasma or liquid component of the blood.
  • Platelets: they help the blood to coagulate, stopping bleeding.

What is the complete blood count and why is it so important?

A complete blood count, as indicated at the beginning of the note, provides the possibility for the doctor to know the patient's general health status. Thus, for example, not only can it be useful to know if a certain organ of the body is working properly (as it could be the case of the liver or kidneys), but to diagnose a certain disease especially if the person presents a series of symptoms such as fatigue, weakness, bleeding, fever or inflammation.

Among the diseases or pathologies that a hemogram can diagnose we can mention especially anemia (condition in which there is a lack of healthy red blood cells sufficient to transport an adequate level of oxygen to different tissues of the body, 1) or leukemia ( cancer of white blood cells, 2).

In turn, once diagnosed a certain blood disorder that affects the blood cell count, the blood count allows to monitor its evolution, as well as monitor whether the prescribed medical treatment is being adequate or if the patient is taking medications that could affect to the normal count of blood cells.

What can the results of a blood count indicate if the values ​​are altered?

If the presence of an altered value is observed in the complete blood count, depending on which the abnormal element is, it will be related to a certain cause. For example:

  • Red blood cell count, hematocrit and hemoglobin:If the value of these three elements is below normal, the person could have anemia. However, a higher than normal count (which is medically known as erythrocytosis), or elevated hematocrit or hemoglobin values, may be related to heart disease or undiagnosed disease.
  • White blood cell count:If the value of white blood cells is less than what is considered normal, it could be caused by an autoimmune disease that attacks and destroys white blood cells, bone marrow disorders, consumption of certain medications that decrease the count of these cells, or cancer. If the count is high, it could indicate the presence of an infection or inflammation.
  • Platelet count:The presence of thrombocytopenia (platelet count below normal) or thrombocytosis (platelet count above) may be the result of a side effect of a medication, or the existence of an undiagnosed disease.

Results and normal values ​​of the blood count

Although these figures may vary slightly from one laboratory to another, here are the normal results of a complete blood count for adults:

Red blood cell count

Men: 4.32-5.72 trillion cells / L

Women: 3.90-5.03 trillion cells / L


Men: 13.5-17.5 grams / dL

Women: 12.0-15.5 grams / dL


Men: 38.8-50.0%

Women: 34.9-44.5%

White blood cell count

3.5-10.5 billion cells / L

Platelet count

150-450 billion / L

Images from Istockphoto


  1. Mayo Clinic staff Anemia. Aug. 08, 2017. Available at: //www.mayoclinic.org/es-es/diseases-conditions/anemia/symptoms-causes/syc-20351360
  2. NIH: National Cancer Institute. Leukemia. November 14, 2017. Available at: //medlineplus.gov/spanish/leukemia.html
  • FAILACE, RENATO & FERNANDES, FLAVIO BENO. Hemogram Interpretation Manual. Madrid: Editorial Panamericana. 2017. 484 pp.
This article is published for informational purposes only.It can not and should not replace the consultation with a Physician. We advise you to consult your Trusted Doctor. ThemesBlood test

In The Lab - Complete Blood Count (CBC) (April 2024)