Blood tests – types, indications, course. Blood count standards

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Diagnostic tests are used for early detection of a possible disease. The earlier the process of its development is captured, the greater the chances of successful treatment, avoiding complications and quick recovery. Some studies can even be said to save lives. This category includes examinations of the heart and circulatory system.

Functions of blood and its components

Blood is a body fluid necessary for life that connects all tissues and organs of the body, therefore it reflects the health of the whole person. In an adult’s body, an average of 5 liters of blood circulates through the veins and arteries. 45 percent of the life-giving fluid is blood cells (white blood cells, red blood cells, and platelets), and 65 percent is plasma.

Red blood cells – erythrocytes – contain a pigment substance (hemoglobin), which carries oxygen and carbon dioxide. Hemoglobin connects red blood cells with oxygen in the lungs. As blood flows throughout the body, it carries the oxygen needed to produce energy. The end product of a chemical reaction that produces energy is carbon dioxide. It is reabsorbed into the blood and excreted in the lungs. Erythrocytes are formed in the bone marrow from the so-called stem cells. Before they reach maturity, they go through various stages of development. The final stage is reticulocytes. For the production of red blood cells, you need iron, vitamin B12 and folic acid.

If the body lacks any of these components, abnormal forms of cells are formed, recognizable in a morphological examination. The life expectancy of a red blood cell is approximately 120 days. The process of selecting and eliminating old cells (haemolysis) takes place in the spleen and produces a bile pigment called bilirubin.

See also: Healers’ plasma is lacking, and there is no supply

Blood tests – when to do?

Blood tests can provide information on a wide range of medical conditions and a person’s overall health.

Your doctor may order a blood test during a routine checkup or if there are signs and symptoms of an underlying problem. People being treated for chronic diseases can see their doctor regularly for blood tests. Anyone with persistent symptoms should see their doctor for testing.

Also, people taking certain blood-thinning medications may need regular blood tests. Their doctor can advise them on the frequency of testing based on risk factors and individual needs.

See also: Do you have blue blood? Test the blood!

Blood tests – what do they look like?

Depending on the reason for taking your blood test, you may need to avoid eating or drinking before the test. It happens because some foods and drinks can affect your blood test results.

Typically, a blood test is performed by a healthcare professional inserting a needle into a vein, usually the arm, to collect blood. Often a healthcare professional will wear a rubber band around your arm to see the veins in your arm more clearly and clean the area with an alcohol swab before inserting the needle. The test subject may be asked to clench their fists to make the veins stand out more.

The test subject may feel a slight twinge that only lasts a second or two as the needle enters a vein. It usually takes no more than 3 minutes to obtain a sample for a blood test. The test person may feel faint after taking blood. Anyone who feels dizzy should sit until the feeling is gone.

The puncture site will be covered with gauze and bandage. The arm may feel a little sore after a blood test for several hours. A small bruise may appear where the doctor has inserted the needle.

Blood tests – morphology

It is the basic diagnostic test in medicine. Thanks to it, we learn about the blood picture, we gain information about the number and condition of blood cells. The results of the morphology provide the physician with very important information about the state of health of the examined person, as they allow them to pick up the signals of various diseases. As a preventive measure, it is recommended to perform morphology once a year. You should come for the examination on an empty stomach – at least 8-10 hours should elapse from the last meal. Blood for morphological examination is most often taken from a vein.

See also: What do lowered EOS mean in morphology?

Morpholofia — norms

Blood count reference values:

1. Erythrocytes – males: 4,5-5,9 million / µl; women: 4,0-5,2 million / ul
2. Leukocytes – 4000-9000 cells / µl
3. Thrombocytes – 140- 000 cells / µl
4. Hemoglobin – males: 14,0 – 18,0 g / dl; women: 12,0-16,00 g / dL
5. Hematocrit – men: 42-52%; women: 37-47%
6. MCH – 28-34 pg
7. MCV – 83-93 fl (µm to the power of 3)
8. MCHC – 32-36 g/dl
9. Reticulocytes – 7-15% of erythrocytes

By viewing the results, we can see which values ​​deviate up or down from the given reference values. However, let’s not make the diagnosis ourselves, but show the printout to the doctor. It is worth knowing that the ranges of reference values ​​provided by individual laboratories may differ from each other by up to 10 percent, which is due to the use of different measurement methods.

It is also worth remembering that various factors affect the test result. In addition to the disease, it is also age, sex, body hydration status, and in women, also the phase of the menstrual cycle. This means that, for example, the normal number of red blood cells may differ between a 70-year-old man and a young girl. Yet another standard will apply to a pregnant woman.

Blood tests – hemoglobin

It is the red blood pigment, the main component of red blood cells, and binds most of the body’s iron. Increased hemoglobin is generally associated with increased red blood cell counts. A lowered hemoglobin value occurs after hemorrhages and iron deficiency anemia.

Blood tests – hematocrit

This term is used to describe the percentage of all blood cell components in the total blood volume. Its value is slightly different for men and women, because one liter of blood in women contains about 410 million blood cells, and in men – about 460 million. Differences in hematocrit values ​​may result not only from sex but also from age.

See also: What is low hematocrit associated with?

Blood tests – erythrocytes (red blood cells)

It is a collective term that includes three different values ​​that characterize the state of red blood cells. They are measured by the number of red blood cells, hemoglobin concentration and hematocrit value. Based on the parameters of the red blood cells, it is easier to determine the cause of anemia.

#MCH: mean red blood cell hemoglobin content, measured in picograms (pg = 10 to the 12 g power).

#MCV: The mean volume of red blood cells reported in cubic micrometers (µm to the power of 3 or femtoliters (fl = 10 to the power of 15L). Calculating this value can tell if the blood cells are (too) large or (too) small.

#MCHC: Mean red blood cell hemoglobin concentration in grams per deciliter (g / dL). This value tells you whether the erythrocytes contain (too) much or (too) little hemoglobin for their size.

Excess erythrocytes in a blood test

Excessive red blood cell counts can occur in people with chronic lung conditions and heart disease. It may also increase when the body loses fluid, such as from vomiting or diarrhea. The body returns to normal when the body is hydrated. The number of erythrocytes naturally increases while staying in high mountains due to the reduced oxygen content in the air. More erythrocytes then guarantees the body an adequate supply of oxygen to the tissues.

Red blood cell deficiency in blood test

We call too few red blood cells anemia or anemia. This condition of the body may be the result of hemorrhages or vitamin and mineral deficiencies. The most common cause of anemia is iron deficiency, more rarely vitamin B12 or folate. Red blood cell deficiency can also be caused by other serious conditions.

See also: Anemia symptoms – characteristics, classifications, causes and effects

Blood tests – leukocytes (white blood cells)

There are significantly fewer white blood cells (leukocytes) in the peripheral blood than erythrocytes, but they are much larger than red blood cells. Leukocytes are found not only in the blood but also in the tissues of many organs and play an important role in the body’s defense (immune) system. An abnormal leukocyte count is often a sign of an inflammatory process in the body.

White blood cells are produced in the bone marrow and lymph nodes and specialize in the spleen and thymus. We distinguish several types of leukocytes (granulocytes, monocytes, lymphocytes), each of them has a slightly different task to fulfill. An additional test that allows to determine the number of individual white blood cells in detail is a peripheral blood smear. It is usually performed automatically by a machine – hematology analyzer.

Sometimes your doctor will order a more detailed microscopic smear, which involves a specialist assessing and counting all types of blood cells under the microscope. This type of smear is free from possible errors resulting from the use of automatic analyzers, and also provides additional information about the shape of blood cells.

Excess of leukocytes in the blood test – leukocytosis

There are various causes for an increase in the number of white blood cells (leukocytosis). The number of leukocytes increases during pregnancy, after meals and with high physical exertion. It is a natural physiological process. A large increase in pathological leukocytes may indicate an acute infection with bacteria, fungi or parasites. The cause may also be hemorrhages, allergies, anaphylactic shock, heart attack, diseases related to metabolic disorders, e.g. diabetes or gout. Cancerous diseases, especially blood cancers (leukemias), also cause leukocytosis.

See also: What do white blood cells in the urine show?

Leukocyte deficiency in the blood test – leukopenia

A reduced number of white blood cells (leukopenia) is most often the result of a viral infection or of diseases such as malaria and typhus. Also, damage to the bone marrow due to radiation with X-rays or the use of certain medications in the treatment of cancer can cause leukopenia.

See also: What do lymphocytes below normal mean?

Blood tests – thrombocytes (platelets)

These cells play an important role in proper blood clotting. There are about 150 – 000 of them in 450 cubic mm of blood. When a blood vessel is damaged, thrombocytes build up at the site of the injury and form a clot with blood clotting factors. Platelets are much smaller than other blood cells. They are also produced in the bone marrow. Their number increases after injury and hemorrhage.

See also: Number of platelets (thrombocytes)

Excess thrombocytes in a blood test

The increase in the number of platelets occurs after serious infections, operations and wounds with high blood loss, after surgical removal of the spleen, and in neoplastic diseases. During bone marrow diseases such as leukemia, the production of platelets increases, but they are usually deficient.

Thrombocyte deficiency in blood test

The reduction in the number of platelets in the blood can occur due to a vitamin B12 deficiency, radiation or certain medications. The number of thrombocytes also decreases as a result of premature cell depletion from infections, allergic diseases, enlargement of the spleen and abnormal blood clotting.

The most characteristic disease of platelets is called thrombocytopenia (thrombocytopenia). Its symptoms are spontaneous bleeding, e.g. from the gums, ecchymosis on the skin. Thrombocytopenia can occur following a viral infection or develop into an autoimmune disease. Platelet abnormalities can occur in diseases of the bone marrow. Then, after the morphological examination, you need to undergo other additional diagnostic tests (e.g. bone marrow biopsy).

See also: WBC – the number of leukocytes in the blood and its importance for health

Why do a morphology?

Periodically performed blood counts enable early detection of many diseases, and if the patient reports after the onset of certain symptoms, he or she can confirm or guide the doctor to the correct diagnosis. First of all, with the help of morphology, the already mentioned blood diseases (anemia, thrombocytopenia, etc.) are diagnosed. Morphology is also an invaluable diagnostic test in detecting neoplastic hematological diseases, such as acute and chronic leukemias, pre-leukemia states and lymphomas.

For diseases that develop slowly and insidiously, for a long time without obvious symptoms, the morphology can be a life-saving test. Such diseases include chronic myeloid leukemia, which, detected in the control morphology at an early stage, gives the patient a chance for a significant extension of life.

See also: What do immature granulocytes mean?

Blood tests – are there any risks?

Doctors and health care professionals generally view blood tests as safe with minimal risk of infection at the site of the blood test.

Anyone who experiences symptoms of an infection at the site of the injection, such as inflammation, swelling, redness and fever, should see their doctor. Excessive bleeding may rarely occur. People who take blood-thinning medications or have other medical conditions that cause excessive bleeding are at greater risk.

Before having a blood test, people who want or need to have a blood test can discuss any possible concerns about side effects with their doctor.

Blood tests – blood enzyme test

An enzyme blood test measures the level of certain enzymes in the body. The body produces enzymes that help control chemical reactions in the body.

Enzymatic blood tests can help your doctor identify specific health problems, including a heart attack. If your doctor suspects a heart attack, he will check the levels of the cardiac troponin enzyme, which the heart releases when the heart cells are damaged.

Blood tests – INR test

The INR test, also known as a blood clotting test, looks for a protein that helps your blood clot. A doctor may order this test if he suspects a person may have a blood clotting disorder.

If a person is taking warfarin or other blood thinners, a doctor will likely use a special blood clotting test as part of a routine checkup.

Blood tests – lipid profile (lipid profile)

If your doctor wants to assess a person’s risk of coronary heart disease or other atherosclerotic problems, they will likely order a lipid profile (lipid profile). The lipidogram will provide information about:

1. low-density lipoprotein (LDL) cholesterol;
2. high-density lipoprotein (HDL) cholesterol levels;
3. total cholesterol;
4. blood triglyceride levels.

It is assumed that the test subject will need to fast for 8 to 12 hours prior to the lipid profile. If the results show abnormal levels of any cholesterol or triglycerides, it could indicate that a person is at a higher risk of developing cardiovascular disease.

Blood tests – metabolic profile

The metabolic profile measures the levels of various chemicals found in the blood plasma. The metabolic profile provides information about bones, muscles and organs.

The metabolic profile includes several blood tests.

1. Calcium Level: Abnormal calcium levels can indicate an underlying kidney or bone related disease, cancer, malnutrition, or other medical conditions.
2. Glucose Level: higher than normal blood glucose levels may indicate diabetes or a risk of developing diabetes. Some people may need to fast before testing their blood glucose.
3. Kidneys: The presence of excess waste products in the blood, such as blood urea nitrogen (BUN) and creatinine, may indicate a kidney problem.
4. Electrolytes: the presence of abnormal electrolyte levels may indicate a problem with dehydration, kidney, or other medical conditions.

See also: Who is at risk of dehydration?

Blood tests in children

It may be necessary to collect blood samples from the very small blood vessels (called capillaries) of the baby or toddler’s finger or heel. This is done by pricking the skin with a needle.

Preparing children for examination or surgery can help reduce their anxiety, increase cooperation, and develop coping skills. This includes explaining to the children what will happen during the test, such as what they will see, feel and hear.

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