Blood count

The Blood count is one of the most frequently used diagnostic methods nowadays, as many diseases are associated with characteristic changes in the blood count. Thus, it enables a quick assessment of the state of health with comparatively little effort for patient and practitioner.

What is a blood count?

A blood count is carried out as follows: First, blood must be drawn from the patient. Usually a vein in the crook of the elbow is used for this. It is not necessary for the patient to stay sober to take the blood sample, but he should refrain from eating fatty foods in the last few hours before the blood sample.

Otherwise there may be more fat particles, the so-called chylomicrons, in the blood sample and lead to incorrect readings. Since the blood or plasma concentrations of some substances fluctuate when standing, it makes sense to take them in a sitting or lying position. It should also be noted that some metrics fluctuate over the course of the day. Therefore, especially follow-up examinations should always be carried out at the same time of day. In the laboratory, mechanical blood count analyzers are used to determine the relevant parameters for the respective clinical issue.

Sometimes a distinction is made between large and small blood counts. For a small blood count, the erythrocyte, leukocyte and thrombocyte count, the hemoglobin concentration, the hematocrit value and the erythrocyte indices MCV, MCH and MCHC are determined. A few other parameters are determined for a complete blood count. Because modern blood count analyzers usually produce a complete blood count immediately, the differentiation between large and small is often no longer made.

Function, effect & goals

The values ​​recorded for the blood count have different meanings. For example, the erythrocytes, i.e. the red blood cells, are important for transporting oxygen in the body. The normal value for the erythrocyte count is 4.0 to 5.5 for women and 4.6 to 6.0 for men. Numbers above or below these limits can have a variety of causes that need to be detected, otherwise serious disruptions in the oxygen supply to the body can occur.

The causes for an increase in the number of erythrocytes are usually a lack of fluids, a lack of oxygen or stress. A reduced number is also known as anemia, technically anemia. In many cases it is an indication of iron deficiency, but can also arise as a result of major blood loss. These blood losses are not always noticed by the patient, as there is no need to be an externally visible wound. Bleeding inside the body and in the intestines can also be responsible for anemia. The parameters MCH, MCV and MCHC are used to further classify anemia.

This allows statements to be made about the quality of the erythrocytes. For this purpose, the hemoglobin content of an individual erythrocyte, the volume and the proportion of hemoglobin in the total volume of red blood cells are considered. If these three values ​​are normal, one speaks of normocytic and normochromic anemia. The formation of new erythrocytes takes place too slowly for the current requirement. A high blood loss is often the cause here. Sometimes, however, the hormonal regulation of erythrocyte formation does not work correctly.

If the MCV, MCH and MCHC are low, it is a question of microcytic anemia. This form is almost always due to an iron deficiency. Iron is important for the production of hemoglobin, the red blood pigment. Iron deficiency therefore means that not enough hemoglobin can be produced. The erythrocytes are then not sufficiently loaded with it and are consequently too small. Various substances are also required as cofactors for erythrocyte formation, especially vitamin B12. If this vitamin is missing, erythrocytes that are too large are produced, which are also loaded with too much hemoglobin. Since a vitamin B12 deficiency can cause further damage, a substitution can be initiated immediately based on the blood count.

Finally, the thrombocyte and leukocyte counts are important parameters of the blood count. Platelets are also colloquially called "blood platelets". They are important for blood clotting, for example after injuries. The leukocytes, also known as "white blood cells", have a variety of tasks in the context of the immune system. If the leukocyte values ​​change significantly, further diagnostics must follow, as life-threatening diseases can also be the cause.

Risks, side effects & dangers

Overall, the acquisition of a blood count is a cost-effective and easy-to-use method for checking the state of health of a patient or finding the cause of symptoms. In addition, the evaluation of a blood sample only takes a short time. In most cases, results are available after just one day.

For the patient, the blood collection is also associated with little effort, undesirable effects are not to be expected. In addition to the aforementioned changes in the blood count, there are many other characteristic changes that can be used to detect diseases with a high degree of probability. Values ​​that go beyond the standard parameters can also be requested as part of the blood analysis, so that a differentiated diagnosis is easily possible. For example, a precise hormonal status can be recorded and effective treatment can be initiated on this basis.

An adequate follow-up of chronic diseases via the blood count is also possible. In this case, too, changes can be made if necessary and the treatment adjusted. All of these advantages are responsible for the fact that the blood count plays a major role in diagnostics in almost all disciplines. With comparatively little effort, it provides valuable information on how to proceed.