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Health

Blood test

, medical expert
Last reviewed: 06.07.2025
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Blood analysis is the most common method of research, without which modern diagnostics is not possible. Various types and methods of analytical blood tests help modern medicine to quickly and accurately identify hundreds of thousands of ailments.

Blood tests should usually be taken early in the morning, preferably on an empty stomach. This is explained quite simply. The blood flow in the human body circulates continuously, daily and every minute. Blood is extremely susceptible to the influence of many factors, both external and internal. It is precisely the internal factors that will be the subject of study during the analysis, in order for the clinical picture to be clearer, external factors are excluded if possible. Blood composition can be affected by food, stress, and even physical overwork.

Blood analysis and types of analytical studies:

  • Clinical, which is often referred to by the abbreviation CBC – complete blood count;
  • Biochemical;
  • Hormonal studies;
  • Analysis that determines allergens.

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General and clinical blood tests

A general, clinical blood test is the most frequently prescribed test, which is probably familiar to many of us. This study determines the quantitative indicators of the main elements of the blood. The first on the list is hemoglobin - an indicator of the saturation of the blood with an important element that provides many functions of the body - oxygen. Hemoglobin is part of the red blood cells, which are also determined in the CBC.

Determining the hematocrit helps to understand how many red blood cells are in percentage terms in a given amount of blood. In addition, an important leukocyte index is determined, showing the presence of intoxication in the body caused by inflammatory processes or infection. Determining the ESR (how quickly red blood cells settle in a special laboratory tube) helps to identify the inflammatory process when it is so hidden that it cannot be determined by counting the number of leukocytes. Platelets are also counted, the smallest cells in the bloodstream, which are responsible for blood clotting processes.

It is these small blood cells that protect a person from excessive blood loss by sticking together and transforming into clots. Clinical analysis is carried out to determine and clarify the following conditions and diseases:

  • Anemia;
  • Exhaustion, chronic weakness;
  • The appearance of hematomas and bruises without objective reasons (injuries, contusions);
  • Blood loss;
  • Infectious diseases;
  • Possible diseases of the hematopoietic system;
  • Monitoring the effectiveness of drug therapy;
  • Condition before surgery.

Biochemical blood test

A biochemical study determines enzyme indices, as well as the amount of lipids, proteins, some types of pigments (bilirubin), vitamins and nitrogenous substances. Biochemistry shows dysfunctions of many organs, such as the liver, genitourinary organs, and kidneys. This analysis can detect rheumatism, changes in water-salt balance, and the amount of microelements. In addition to clarifying information about the diagnosis itself, a biochemical study helps determine the stage and severity of the disease. This type of analysis is performed by taking blood from a vein.

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Blood test for hormones

A blood test that determines the level and ratio of hormones helps to assess the condition of the adrenal glands and thyroid gland. Many endocrine diseases require such a study.

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Blood test for allergens

Determination of allergens helps to identify the real "enemy" - a harmful agent that provokes the immune system to an aggressive reaction. This analysis determines the level of specific immunoglobulins IgE, which are markers of allergic reactions.

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Blood test for tumor markers

Determination of tumor markers helps to identify proteins that are formed in neoplasms. Tumor markers determine the severity of the process and can also help to clarify whether the formation is benign or whether it is already moving to a stage that threatens the patient's life.

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A blood test that determines the level of vitamins in the body

This study is prescribed when there are all the signs of vitamin deficiency and microelement deficiency in the body. Also, with the help of this analysis, hypervitaminosis is determined, which can occur as a result of uncontrolled independent intake of certain vitamins, especially vitamin A and C. In the laboratory, a biochemical blood test is carried out to simultaneously determine the concentration of vitamins B12, folic acid and the level of iron, potassium, calcium, sodium. Other groups of vitamins (C, B1, D, E, B5) are not subject to precise determination, their calculation is carried out in a complex manner

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Blood test for drugs

Blood analysis to determine the concentration of drugs in the body helps to monitor pharmacokinetics during a course of drug treatment. Drug monitoring is carried out using a microbiological or spectrophotometric method. Such information allows for therapeutic control of the action of prescribed drugs, to identify their inefficiency and promptly replace them with more effective ones.

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Blood drug test

Blood testing for drug detection is one of many parts of forensic practice.

Laboratory blood tests for drugs are significantly less informative than urine tests, but blood can be used to determine the frequency and duration of chemical substance use. Such analysis can detect traces of drugs used 3-4 months ago, before the test. The quarterly test is designed to establish the fact of use, it detects even small traces of amphetamines, cannabinoids, opiates that were introduced into the body long before the test.

Blood tests are done fairly quickly, and the time it takes to process the results depends on the type and method of testing. The fastest tests are the complete blood count (CBC), as well as biochemical tests. All other types can take from two to seven days to process. The results are recorded on a special form, which contains the recorded norms and identified blood indicators. The ratio of the norm and deviations from it allows the doctor to specify the diagnosis and more accurately build treatment measures. It should be noted that independent decoding of the test may cause false alarm. The norms of the indicators depend on the age of the patient, and the results are interpreted in conjunction with other factors - visual inspection, comparison with urine tests and other types of research. Therefore, it is better to provide the decoding of the tests to a specialist.

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