Methods of blood testing

Despite the indisputable importance of data obtained with the help of special methods, the generally accepted methods of clinical examination of the patient can also provide valuable information.

Complaints

In most patients, complaints are nonspecific and reduce more often to general weakness, headaches, dyspnea, abdominal pain, and bleeding. Often there is an increase in body temperature (from subfebrile to fever, accompanied by chills, sweats), loss of appetite and weight loss (also common symptoms of many diseases of various organs and systems). Severe anemia is a characteristic manifestation of increased blood loss in blood disease, but often a consequence of repeated bleeding with peptic ulcer of the stomach, hemorrhoids, gynecological pathology.

Weight loss, often combined with loss of appetite, is especially pronounced in malignant diseases of the blood (leukemia, lymphoma). Sometimes there is a kind of change (distortion) in taste and smell - for example, addiction to the use of chalk, coal, smell of gasoline, which is observed in patients with iron deficiency anemia (chlorosis).

Fever is a frequent manifestation of both the hematological diseases themselves and their infectious complications. The subfebrile state of a protracted character is observed with various anemia, high fever is a typical sign of acute leukemia and lymphogranulomatosis. Usually a fever of this origin is followed by profuse sweats, chills, weight loss, general weakness and malaise.

Complaints about hemorrhage, manifested hemorrhagic rashes on the skin, nosebleeds, gastrointestinal and uterine bleeding, are quite typical for blood diseases.

A significant increase in the liver and spleen can be manifested by pain, by stretching the capsule, especially if the organ increase is rapid.

[1], [2], [3], [4], [5], [6], [7],

Anamnesis of the disease

When studying the history of the disease, it is very important to find out the possible causes of the disease. In this regard, it should be borne in mind that often the changes in blood are secondary and are one of the signs of the disease of other organs and systems. Particular attention is drawn to the possible hematological effects of previously taken medications, including on the patient's own initiative - with widespread self-medication with analgesics, laxatives, tranquilizers.

When clarifying the family history, it is important to find out if the relatives have jaundice, anemia, cholelithiasis (hereditary hemolysis), bleeding should be asked about similar manifestations in close relatives, it is important to establish the fact of the death of brothers and sisters in early childhood. The prevalence of the disease among male relatives in different generations is especially characteristic of hemophilia.

[8], [9], [10], [11], [12], [13]

Physical methods of blood testing

Physical examination is carried out in full, including elements of general examination and the study of individual organs and systems.

Skin and mucous membranes can be changed in connection with a direct change in the properties of blood flowing through the capillaries, as well as the deposition of pigments in the skin.

Pallor is due to anemia, and reddening of the skin with erythrocytosis, although transitory pallor can be associated with exposure to cold, and erythematous complexion with frequent use of alcohol, the effect of both low and high temperatures, etc. A more reliable sign of anemia and erythrocytosis - pale color of mucous membranes and nail beds. Jaundice coloration of the skin and mucous membranes often happens during hemolysis.

Petechia and ecchymosis - hemorrhages on the skin due to vasculitis or blood clotting disorders.

Traces of scratching associated with pruritus are characteristic of lymphogranulomatosis.

The change in the shape of the nails, their thickening, the appearance of striation - signs of iron deficiency.

The appearance of ulcers on the mucous membrane of the mouth is characteristic of agranulocytosis. With leukemia, infiltration of the gums, their hyperemia, bleeding can occur. The tongue with smoothed papillae occurs in iron deficiency and pernicious anemia.

Lymph nodes are often involved in the pathological process. It is advisable to consistently feel the lymph nodes, beginning with the occipital, then palpate submandibular, sub-chin, cervical, supraclavicular, axillary, ulnar, inguinal. Palpation should be carried out by soft circular motions of fingertips. Pay attention to their size, consistency, soreness. The increase in cervical and supraclavicular nodes may be regional in nature (more often with tonsillitis and the presence of carious teeth). Nodes located in the thorax at the roots of the lungs can be detected radiographically, and in the abdominal cavity - using computed tomography or ultrasound. The increase in lymph nodes is characteristic of leukemia, primarily chronic lymphocytic leukemia, as well as lymphogranulomatosis.

Changes in bones occur quite often. Pain in the bones can be either generalized (with leukemia) or localized (with myeloma and bone metastases). It is advisable to carry out a feeling of the surface of the bones to identify possible foci of diseases.

Liver enlargement is detected with the help of both physical (palpation, percussion) and instrumental methods (ultrasound and computed tomography). Hepatomegaly is detected with leukemia, hemolysis.

The study of the spleen is very important. The most reliable method of detecting an enlarged spleen is her palpation. Percutally, the increase in this organ is less evident (see the chapter on liver diseases). Normally, the spleen is not probed. Pay attention to the size of the spleen, its consistency, soreness. With pronounced splenomegaly, the lower pole can protrude far from under the left costal arch. Sometimes it is advisable to feel the spleen in position both on the right side and on the back.

In the left upper quadrant of the abdomen, the formation associated with other organs (kidney, left lobe of the liver, pancreas, large intestine) can be probed. Sometimes it is difficult to distinguish them from the spleen, and in these cases, you should use ultrasound and other instrumental methods to identify the palpable formation.

In case of blood diseases, the nervous system is often affected, especially with vitamin B12 deficiency, leukemia and hemorrhagic diathesis.

Additional research methods

In diseases of the hematopoietic system, the following special methods of investigation are used: general clinical analysis of blood, examination of bone marrow points, lymph node, spleen. Histological, cytochemical, cytogenetic, X-ray, ultrasound, radioisotope methods are used.

At the general or common analysis of a blood define the hemoglobin content, the number of erythrocytes, other parameters, often leukocytes, thrombocytes, count the leukocyte formula, determine ESR. This analysis can be supplemented by determining the number of reticulocytes.

Usually, the capillary blood obtained by pricking into the flesh of the fourth finger of the left arm or the blood from the ulnar vein are examined. In this case, needle-scarifiers are used, which are then washed and sterilized by boiling or by placing them for 2 hours in a drying oven at a temperature of 180 ° C.

The skin in the injection site is wiped with a cotton swab dampened with alcohol, then with ether. It is better to make an injection to a depth of 2-3 mm.

It is desirable to take blood in the morning on an empty stomach. However, if necessary, a blood test can be performed at any time of the day.

Methods for determining hemoglobin level, counting of erythrocytes, leukocytes, platelets, and also the leukocyte formula are considered in detail in special publications, including the description of modern methods of counting these particles with the help of special electronic counters ("Calloscope", "Kul'ter").

Despite the great importance of the study of peripheral blood, it must be emphasized that the results of a general blood test should be evaluated only in conjunction with all other clinical data, especially in case of dynamic observation of the patient.

The increase in the number of red blood cells (erythrocytosis) in the blood can be short-term (for example, with great physical exertion, in mountainous conditions) or be of a longer duration (chronic pulmonary insufficiency, congenital heart diseases, erythremia, kidney tumors). Usually, in both cases, an increase in hemoglobin is noted.

The number of erythrocytes and hemoglobin levels decrease with anemia (especially rapidly with severe hemolysis, bleeding), as well as in acute and chronic infections (influenza, sepsis, etc.), chronic kidney failure and, of course, under the influence of various drugs (levomycetin , cytostatics, etc.). In a number of these situations, a change in the number of reticulocytes is observed; their decrease in aplastic, iron deficiency and megaloblastic anemia, leukemia; their increase in hemolysis, acute posthemorrhagic anemia; is the clinical interest of the appearance of significant reticulocytosis with dynamic observation a few days after the appointment of vitamin B ₁₂ in the case of pernicious anemia (reticulocyte crisis on the 7-10th day of treatment).

An indication of insufficient maturation of red blood cells is the appearance in the red blood cells of the so-called basophilic granularity, which is especially characteristic of anemia associated with lead intoxication. When erythropoiesis is disturbed in the peripheral blood, the red cell germ-containing nuclei can be detected - normoblasts.

A large clinical significance is the more frequent morphological changes in red blood cells, such as the presence of erythrocytes of different sizes (anisocytosis), which can be combined with changes in their shape (poikilocytosis), the predominance of erythrocytes of small microcytosis) or large (macrocytosis) sizes (less than 6 μm or more, respectively 8 μm with a normal average erythrocyte diameter of 7.2 μm). The determination of the erythrocyte diameter makes it possible to graphically register the distribution of erythrocytes in magnitude in the form of the so-called Price-Jones curve, on which micro- and macrocytosis is especially clearly revealed. Usually, these conditions indicate a change in the hemoglobin content in erythrocytes, determined by the color index (or, more commonly, by the weight content of hemoglobin in erythrocytes - the ratio of hemoglobin in 1 liter of blood to the number of erythrocytes in the same volume, one erythrocyte contains 27-33 ng of hemoglobin). With microcytosis, a decrease is seen, with macrocytosis, an increase in the hemoglobin content in one erythrocyte. Thus, the most common iron deficiency anemia is usually accompanied by microcytosis and a reduced content of hemoglobin in one erythrocyte.

It is important to determine the ratio between the volume of erythrocytes and the volume of plasma - this indicator was called the hematocrit number, or hematocrit. Special centrifuges are created in which a hematocrit tube is placed. As a result, the study determines how much of the blood is made up of red blood cells. The hematocrit is measured electronically with the help of Kulter and the Celloscope simultaneously with the calculation of the average volume of the erythrocyte and the total volume of red blood cells, after which, knowing the volume of blood, the hematocrit is determined. When the blood thickens (with vomiting, diarrhea, other situations with a large loss of fluid), the volume of erythrocytes increases due to a decrease in the volume of plasma.

Of great clinical importance are the results of the study of leukocytes - the total number of leukocytes and the percentage of their individual forms.

Already in itself, the change in the total number of leukocytes both in the direction of increase (leukocytosis) and downward (leukocytopenia, leukopenia) can be an important diagnostic sign, the value of which increases with repeated blood tests (the increase of these changes undoubtedly indicates a progression of the process ). But especially important is the value of the leukogram associated with this study - the leukocyte formula (the percentage in the peripheral blood of individual forms of white blood cells), since it is the leukocytes that react earlier and faster than other blood elements to external and internal changes. Leukocytosis is typical for acute bacterial infections. In this case, shifting the formula to the left - an increase in the content of young forms of neutrophils (rod-shaped), the appearance of young neutrophils indicates the early stage of the process. A high neutrophilic leukocytosis is characterized by localized inflammatory processes (lung abscesses, etc.), including the development of tissue necrosis (burns, myocardial infarction), malignant tumors during decay, as well as rheumatism, endogenous and exogenous intoxications (uremia, diabetic acidosis , poisoning with fungi, etc.), medicinal effects (corticosteroids). Particularly should be called myeloproliferative diseases (chronic myeloid leukemia, erythremia), in which, in addition to leukocytosis, there are also changes in the leukocyte formula. Leukemoid reactions resemble blood changes in leukemia (significant leukocytosis with "rejuvenation" of the formula), but they are reactive in nature, being associated, for example, with tumors.

Eosinophilia occurs in allergies (bronchial asthma, drug intolerance), parasitic infestations (trichinosis, ascariasis, etc.), skin diseases (psoriasis, pemphigus), tumors, other diseases (nodular periarteritis); basophilia - with myeloleukemia, erythremia; with a rare disease - mastocytosis there is infiltration of these cells by various organs; monocytosis is observed in infectious endocarditis, tuberculosis, systemic diseases (systemic lupus, rheumatoid arthritis).

Lymphocytosis is characteristic for viral and chronic bacterial infections, lymphatic leukemia, and lymphomas.

Leukopenia is a characteristic sign of some infections (especially viral infections), the effects of ionizing radiation, many drugs (especially immunosuppressants), bone marrow aplasia, autoimmune systemic diseases (systemic lupus erythematosus, etc.), redistribution and sequestration of leukocytes in organs (anaphylactic shock , Felty's syndrome, splenomegaly of different origin). Particularly should be called agranulocytosis, which can be myelotoxic (radiation, cytotoxic agents) and immune (systemic lupus erythematosus, drug lesions).

Qualitative changes in leukocytes have less clinical significance. Toxic granulation of neutrophils is observed in severe infections and toxicoses. LE-cell phenomenon is observed in systemic lupus erythematosus and includes the appearance of "lupus cells" (LE cells) - neutrophilic leukocytes, including a phagocytic homogeneous nuclear material. In addition, there are hematoxylin bodies (nuclear material) and "rosettes" - the formation of neutrophils, a ring surrounding the nuclear material.

ESR is most dependent on the protein composition of blood plasma, especially on the content of fibrinogen, immunoglobulins. The degree of acceleration depends on the relationship in the content of some proteins. Especially marked ESR increases with the appearance in the plasma of proteins - paraproteins, which is typical, for example, for myeloma. At present, paraproteins can be identified.

The pH of the plasma also affects the ESR (decreases with acidosis, increases with alkalosis), with anemia, ESR increases, with erythrocytosis - slows down.

The bone marrow examination is widely used in clinical practice. The material for its study is obtained with puncture of spongy bones, usually the sternum in the upper third of the body (sternal puncture), the ilium (trepanobiopsy). The need for these studies arises in a variety of situations: anemia, the nature of which has remained unclear (despite various non-invasive studies); leukemia, pancytopenia, tumor process (to exclude or confirm metastases).

A cytochemical study of leukocytes is used to identify, in particular, tumor lesions of the blood. Of particular importance are the differences in granules in some types of granulocytes at different stages of their differentiation, which is particularly effectively detected with monoclonal antibodies to membrane proteins that make it easier to distinguish lymphocyte subpopulations. The patients' blood is examined for the content of peroxidase, alkaline phosphatase, esterases and a number of other enzymes in leukocytes.

Cytogenetic research is carried out to detect anomalies in the number and morphology of chromosomes of cells. Thus, the appearance of the Philadelphia chromosome in chronic myelogenous leukemia is well known.

Investigation of hemorrhagic syndrome is also important, as violations of blood clotting with the development of bleeding may be associated with a lack of platelets, a change in coagulation due to a violation in the blood of humoral coagulation factors, pathological "fragility" of blood vessels.

Clinical manifestations of hemorrhagic syndrome can sometimes suggest its causes. Thus, petechiae (small hemorrhages on the skin) are more often associated with a lack of platelets or damage to the vascular wall, large subcutaneous hemorrhages (ecchymoses) suggest a violation of blood coagulability due to liver disease, hemarthrosis indicates hemophilia.

The combination of small petechiae and ecchymoses is possible due to the presence of vascular lesion, most likely an immunocomplex nature.

Teleangiectasia on the lips and mucous membranes can explain hemoptysis, intestinal bleeding, hematuria.

In the processes of blood coagulation blood platelets circulating in the blood play an important role, which are formed from bone marrow megakaryocytes.

Calculation of the number of platelets is performed in a blood smear per 1000 erythrocytes. Knowing the number of erythrocytes in 1 μl of blood, the number of platelets is also revealed. Electronically-automatic counters of the type "Celloscope" and "Kulter" are also used.

The decrease in the number of platelets (thrombocytopenia) and the resulting bleeding develop significantly more often than thrombocytosis and occur in the case of Verlhof disease, autoimmune, medicinal, radiation effects.

The state of thrombocyte-microcirculatory hemostasis reflects such indicators as the duration of Duke I bleeding and the retraction of the blood clot.

The resistance of the capillaries is estimated with the help of the "pinch symptom": a pinch appears on the place of the pinch. The "harp symptom symptom" has a similar meaning: the cuff of the tonometer is applied to the shoulder for 3 minutes at a pressure of 50 mm Hg. With a positive symptom a significant amount of petechia appears.

With the help of special devices it is possible to study such properties of platelets as aggregation and adhesion.

Coagulation hemostasis is characterized by an integral indicator of coagulation - the time of coagulation of whole blood. Clinical significance also has the definition of thrombin and prothrombin time, prothrombin index, and a number of other indicators.

[14], [15], [16], [17], [18], [19], [20]