General blood analysis

, medical expert
Last reviewed: 20.11.2021

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General clinical research is one of the most important diagnostic methods, which accurately reflects the reaction of the hematopoietic organs to the effect of various physiological and pathological factors. In many cases, it is of great importance in the diagnosis, and in diseases of the hematopoiesis system, he is given a leading role.

The concept of "general clinical study of blood" (a general blood test) includes determining the concentration of hemoglobin, counting the number of erythrocytes, color index, white blood cells, erythrocyte sedimentation rate (ESR) and leukocyte formula. In necessary cases, additionally determine the time of blood coagulation, the duration of bleeding, the number of reticulocytes and platelets. At present, most of the parameters are determined on automatic hematological analyzers, which allow simultaneous examination of 5 to 36 parameters, the main ones of which include hemoglobin concentration, hematocrit, erythrocyte count, MCV, mean hemoglobin concentration in erythrocyte, mean hemoglobin in erythrocyte, half-width of erythrocyte distribution by size, the number of platelets, the average platelet volume, the number of leukocytes.

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Preparing for a general blood test

For the clinical analysis, capillary blood is used, which is obtained from the finger of the hand (usually anonymous, less often - middle and index) by puncturing the lateral surface of the soft tissues of the terminal phalanx with a special disposable lancet. This procedure is usually performed by a laboratory assistant.

Before taking blood, the skin is treated with a 70% alcohol solution, the first drop of blood is blotted with a ball of cotton wool, and the following drops are used to make blood smears, set in a special glass capillary to determine the rate of erythrocyte sedimentation, as well as assess other indicators, .

The basic rules of taking blood from the finger

To avoid mistakes in performing a clinical blood test, you need to follow certain rules. The analysis of blood from the finger should be given in the morning hours after an overnight fast, ie, 8-12 hours after the last meal. The exception is when a doctor has a suspicion of developing a serious acute illness, such as acute appendicitis, pancreatitis, myocardial infarction, etc. In such situations, blood is taken regardless of the time of day or meal.

Before visiting the laboratory, moderate use of drinking water is allowed. If the day before you used alcohol, it is better to donate blood for analysis not earlier than 2-3 days later.

In addition, before taking blood for research, it is desirable to avoid excessive physical exertion (cross, weight lifting, etc.) or other intense effects on the body (visiting steam baths, saunas, bathing in cold water, etc.). In other words, the regime of physical activity before giving blood should be the most common.

Do not knead and rub fingers before taking blood, as this can lead to an increase in the level of leukocytes in the blood, as well as a change in the ratio of liquid and dense parts of the blood.

The main indicators of clinical blood analysis and what can indicate their changes

The most important for assessing the health status of the subject are such indicators as the ratio of the volume of the liquid and cellular parts of the blood, the number of cellular elements of blood and the leukocyte formula, as well as the content of hemoglobin in erythrocytes and erythrocyte sedimentation rate.

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