Blood count under the microscope: How to decipher its abbreviations and navigate the tangle of technical terms?

Why is a blood count complex and "complex"?

A complete blood count (abbreviation CBC or Complete Blood Count) is the most frequently performed laboratory test, providing detailed information about the size, quantity and functionality of blood cells (1) (2). In addition to a blood count, a biochemical test is also often performed on the blood. This can be basic or, depending on the clinical condition and the presumed diagnosis, the doctor selects specific parameters that he wants to determine in the blood. It helps in assessing the metabolism of substances and the function of certain organs. A complete blood count together with a biochemical blood test helps to detect specific diseases (e.g., GGT assessment helps to detect liver disease and biliary tract in cases of suspected alcoholism).

A complete blood count typically includes measurements of the number of red blood cells (they carry oxygen), the amount of hemoglobin (oxygen binds to them in red blood cells), and the hematocrit (the proportion of red blood cells in the total blood volume), the number of platelets (they participate in blood clotting), and the number of white blood cells (they fight infection). A leukocyte differential is often added to the complete blood count, which determines the representation of individual types of white blood cells (1) (3) (15), which explains its complexity:

1. A large number of parameters - since it provides information about different types of cells and their properties, it can be confusing for a layperson.
2. Interdependence - the values ​​​​affect each other (e.g. a decrease in hemoglobin may be related to a low number of red blood cells, which is a sign of anemia).
3. Different reference values ​​– norms vary according to age, gender, health status, but also the laboratory where the test is performed.
4. Possible deviations do not always mean disease – values ​​​​deviating from the norm do not always mean disease (but, for example, dehydration, stress or recent infection), which makes interpretation difficult.

Therefore, it is necessary to interpret the results of the blood count in the context of the clinical condition, medical history and other examinations. In case of deviations from the norm, it is important to consult a doctor.

#1 Red blood cells, hemoglobin and hematocrit

You will definitely come across the abbreviation RBC or Ery in the blood count results, both terms mean red blood cells (RBC = Red Blood Cells; Ery = erythrocytes). RBC also means Red Blood Count or the number of red blood cells in a certain amount of blood, in our country it is always calculated in one liter (4).

An obvious part of the blood count are also the parameters of the erythrocytes:

1.  Mean red blood cell volume (abbreviation MCV = Mean Corpuscular Volume) or the average size of red blood cells; (4) it is given in femtoliters, fl (5).
2.  Hemoglobin content in red blood cells (abbreviation MCH = Mean Corpuscular Hemoglobin) or the average mass of hemoglobin in red blood cells, determines the average amount of hemoglobin in red blood cells (4); it is given in picograms, pg (6).
3. Mean corpuscular hemoglobin concentration (MCHC) is determined based on the volume of red blood cells (4); it is given in grams per liter or grams per deciliter, or in millimoles of hemoglobin per red blood cell (7).
4. Red Cell Distribution Width (RDW) indicates the variability of the size of red blood cells in a blood sample, i.e. the degree of difference in the size of red blood cells (if the number is low, all blood cells are almost the same size, if it is high, there is a noticeable difference between the largest and smallest red blood cells); it is given in percentage (8).
5. Hematocrit (HCT) – the ratio of the volume of red blood cells to the total blood volume or the proportion of red blood cells in the total blood volume (4); it is given in percentage, on the result sheet it is written using a decimal number (9).

#2 White blood cells and differential

If you come across the abbreviation WBC or Leu in a report from your doctor, know that both terms mean white blood cells (WBC = White Blood Cells; Leu = leukocytes). In the basic blood count, you will find the total number of white blood cells, in the case of an extended blood count, it is also supplemented by the so-called differential (which measures all types of white blood cells). These are recorded either as an absolute number (expressed by the abbreviation "abs") or a percentage (%) of white blood cells (4).

In a blood count with a differential, note the following parameters:

1. White blood cell count (WBC) or the number of all types of white blood cells together in a certain amount of blood (in our conditions, this is always in one liter of blood).
2. The number of neutrophils or cells fighting on the front line against bacterial and fungal infections (4), the representation within all white blood cells is given as a percentage.
3. The number of monocytes, or cells that clean up the remnants of molecules after an infection and alert other white blood cells to harmful invaders such as bacteria and viruses (4), (16).
4. The number of lymphocytes, or cells that produce antibodies, which help the immune system remember previous infections, coordinate immune responses, help remove foreign substances, fight viral infections, and attack cancer cells (4), (11) (16).
5. The number of eosinophils, or white blood cells that fight parasitic infections and are important in allergic reactions (4).
6. The number of basophils, or cells that release histamine and heparin in allergic reactions, prevent blood clotting, and help fight parasites (4), (16).
7. A number of immature granulocytes, or white blood cells that have not yet fully developed (4).

#3 Platelets

In the blood count, you will find the following parameters related to platelets:

1. Platelet count (PC) or the number of platelets in a certain amount of blood, in our case in one liter of blood (4).
2. Mean platelet volume (MPV) or the average size of platelets (4), given in femtoliters, fl (14).

A blood count test provides information about the composition of the blood. It helps diagnose anemia, infections, inflammatory diseases, blood clotting disorders or leukemia. This test is key to early detection of health problems and monitoring of overall health, so it is important to have it done regularly.