When you go to the hospital for treatment, why do you need to draw blood in most cases?

When you go to the doctor or have a physical examination, a blood test is a basic and extremely important diagnostic method. Whether it is a common cold and fever, or a complex endocrine disorder or tumor screening, doctors often recommend blood tests to patients. Although this procedure seems simple, the medical principles and clinical significance behind it are very far-reaching. So, what are the uses of blood tests in hospitals?

1. Basic principles of blood test

Blood is a liquid that circulates in the human body and is composed of plasma and blood cells. Plasma contains a variety of components, including water, protein, lipids, sugars, inorganic salts and vitamins. Blood cells include red blood cells, white blood cells and platelets, which respectively undertake important functions such as transporting oxygen, immune defense and coagulation and hemostasis. Blood not only provides nutrition for various tissues and organs of the body, but also participates in physiological processes such as metabolism, immune response and temperature regulation. When a part or system of the body is abnormal, this abnormality is often reflected in the blood components. Therefore, by analyzing blood samples, doctors can obtain rich information about the patient's health status.

2. Main items and significance of blood test

1. Routine blood test

A blood test is the most basic blood test item, which mainly detects the number of red blood cells, white blood cells, hemoglobin and platelets in the blood. Through these indicators, doctors can preliminarily judge whether the patient has common problems such as anemia, infection, inflammation, coagulation dysfunction, etc. For example, a significant increase in the number of white blood cells may indicate a bacterial infection, while a decrease in the number of red blood cells and hemoglobin may be a manifestation of anemia.

2. Blood biochemical examination

Blood biochemistry tests mainly analyze various chemical substances in the blood, such as blood sugar, blood lipids, liver function, kidney function, electrolytes, etc. These indicators reflect the metabolic and functional status of the main organs of the body. For example, abnormal blood sugar levels may indicate diabetes or impaired glucose tolerance; elevated liver function indicators (such as transaminases, bilirubin, etc.) may indicate liver damage; abnormal kidney function indicators (such as creatinine, urea nitrogen, etc.) may indicate kidney dysfunction.

3. Hormone blood test

Hormones are an important class of chemical substances secreted by the endocrine system, which play a key regulatory role in the body's growth, development, metabolism, reproduction and other physiological processes. By testing the hormone levels in the blood, doctors can evaluate the functional state of the endocrine system and diagnose a variety of endocrine diseases such as thyroid dysfunction (such as hyperthyroidism, hypothyroidism), adrenal dysfunction, and diabetes.

4. Infectious disease examination

Many infectious diseases, such as viral hepatitis (type B and type C), AIDS, syphilis, etc., can be diagnosed by detecting pathogen antibodies or nucleic acids in the blood. In addition, when the body is seriously infected, pathogens may multiply in the blood, leading to bacteremia or sepsis. Through blood culture, doctors can identify the specific pathogens of the infection and develop effective treatment plans.

5. Blood system disease examination

Blood system diseases, such as leukemia, anemia, thrombocytopenia, etc., are mainly manifested by abnormalities in the number or function of blood cells. Through blood smears, bone marrow puncture and other examination methods, doctors can understand the morphology and function of blood cells in detail and thus diagnose these diseases.

6. Tumor marker detection

Tumor markers are a class of special proteins or other substances secreted or shed by tumor cells. Changes in their content in the blood may be related to the occurrence and development of tumors. By detecting the level of tumor markers in the blood, doctors can assist in the diagnosis of certain tumors and monitor the treatment effect and recurrence of tumors. However, it should be noted that the test results of tumor markers need to be combined with other imaging examinations and pathological examinations to make a final diagnosis.

Why do you need to draw blood multiple times?

1. Different blood samples are required for different examination items

There are many blood tests, and the testing principles and methods of different tests are different, so different blood samples need to be collected. For example, the blood processing methods and testing instruments required for blood routine tests and blood biochemistry tests are different, so different blood collection tubes must be used for collection.

2. Dynamic monitoring of disease changes

Some diseases develop quickly, and blood indicators will change accordingly. In order to accurately assess the condition and treatment effect, doctors may need to draw blood for multiple tests at different time points. For example, the cardiac enzyme levels of patients with myocardial infarction will rise rapidly within a few hours after the onset of the disease, so multiple blood tests are needed to confirm the diagnosis.

3. Ensure the accuracy of test results

The accuracy of blood test results is affected by many factors, such as operational errors during sample collection, processing, storage and testing. In order to avoid the impact of errors on diagnosis, it is sometimes necessary to repeat the test to confirm the results.

Therefore, blood tests when visiting a doctor are an important means of diagnosing diseases, assessing health conditions, and monitoring treatment effectiveness. Through detailed analysis of blood samples, doctors can obtain a large amount of information about the patient's internal body conditions, thereby formulating a scientific and reasonable treatment plan. Therefore, patients should actively cooperate with doctors in blood tests when visiting a doctor so that they can get a clear diagnosis and effective treatment as soon as possible.