Why do doctors like to prescribe routine blood tests? What diseases can they rule out? What diseases can they detect?

Almost all inpatients and outpatients who have their blood drawn will have a routine blood test. What diseases can this simple blood test detect? If the blood test is normal, what diseases can be ruled out?

Although a routine blood test is called a project, it actually includes many sub-projects. To put it simply, a routine blood test can detect whether we have anemia, bacterial infection, increased thrombocytopenia, etc.

Therefore, when the doctor suspects that we have anemia or inflammation, he will draw a routine blood test.

1. Check whether there is anemia by checking hemoglobin. Hemoglobin is the main component of red blood cells and is responsible for transporting oxygen to organs and tissues and removing carbon dioxide. Hemoglobin can better reflect the degree of anemia.

Hemoglobin reference value

Male: 120-160 g/L

Women: 110-150 g/L

Newborn 170～200g/L

A decrease in hemoglobin is anemia, which can be divided into the following according to severity:

Severe anemia, Hb 31-60 g/L;

Moderate anemia, Hb>61～90g/L;

Mild anemia, Hb is between >90g/L and below the lower limit of normal reference.

Increased hemoglobin is often seen in hypoxia, severe dehydration, cor pulmonale, congenital heart disease, residents of mountainous areas, severe burns, shock, etc.

2. Red blood cell count

Children: (4.2-5.2) × 1012/L

Adult male: (4.0-5.5) × 1012/L

Adult female: (3.5-5.0) × 1012/L

Erythrocytosis:

Non-disease

Increased: impulse, excitement, fear, cold water bath stimulation, hypoxia stimulation; long-term and multiple blood donations.

Reduce: Pregnancy and infants grow and develop rapidly.

disease

Increased: frequent vomiting, excessive sweating, large area burns, hemoconcentration, chronic cor pulmonale, emphysema, altitude sickness, tumors and polycythemia vera, etc.

Reduce: leukemia, acute massive bleeding, iron deficiency, vitamin B12 deficiency, etc.

3. White blood cell count: If we have a fever or suspect inflammation, we will have a blood test to see if the white blood cell count is high as soon as we arrive at the hospital. If the white blood cell count is high, it may be caused by an inflammatory infection, and we will have to take anti-inflammatory drugs or receive anti-inflammatory drug infusions.

Normal reference range:

Adults (4.0-10.0) × 109/L

Newborn (15.0-20.0) × 109/L

Non-disease leukocytosis:

Strenuous exercise, after eating, pregnancy, newborns.

Diseases Leukocytosis:

Acute suppurative infection, uremia, leukemia, tissue damage, acute bleeding, etc.

Diseases Leukopenia:

Aplastic anemia, certain infectious diseases, cirrhosis, hypersplenism, radiotherapy and chemotherapy, etc.

White blood cells are used to initially determine whether there is a bacterial infection. Increased white blood cells can be seen in bacterial infection, bleeding, leukemia, and poisoning.

In clinical practice, the specific disease should be determined based on the typing of white blood cells, clinical manifestations, and other examinations.

There are several types of white blood cells:

Neutrophil N 0.5～0.7 (50%～70%)

It plays an important role in acute infection, and its increase or decrease has the same clinical significance as the white blood cell count.

Eosinophils E 0.01～0.05 (1%～5%)

reduce

Typhoid fever, paratyphoid fever, after major surgery, severe burns, long-term use of adrenal cortex hormones, etc.

increase

Allergic diseases, skin diseases, parasitic diseases, some blood diseases and tumors, such as chronic myeloid leukemia, nasopharyngeal carcinoma, lung cancer and cervical cancer.

Basophil B0～0.0l (0～1%)

Reduce: Allergic shock, seen in overdose of adrenal cortex hormones, etc.

Increased: blood diseases such as chronic myeloid leukemia, trauma and poisoning, malignant tumors, allergic diseases, etc.

Lymphocyte L0.20～0.40（20%～40%)

Reduce: the acute phase of infectious diseases, radiation sickness, cellular immunodeficiency disease, long-term use of adrenal cortex hormones or exposure to radiation, etc.

Increased: infectious lymphocytosis, tuberculosis, malaria, chronic lymphocytic leukemia, whooping cough, certain viral infections, etc.

Monocytes M0.03～0.08（3%～8%)

Increased: infectious or parasitic diseases, active tuberculosis, monocytic leukemia, malaria, etc.

4. Normal reference range of platelets

(100～300)×109/L

Increased: acute massive blood loss and acute infection after hemolysis; polycythemia vera, hemorrhagic thrombocythemia, multiple myeloma, chronic myeloid leukemia and the early stages of certain malignant tumors, etc.

Decreased: aplastic anemia, acute leukemia; hypersplenism; such as disseminated intravascular coagulation, etc.

Of course, there are many items on a routine blood test list, but we usually mainly look at the above items. There are also some other items, which are mainly used to assist in further analyzing the causes when problems are found.

When our routine blood test results are normal, we can completely rule out diseases such as anemia, thrombocytosis or thrombocytopenia, and preliminarily rule out bacterial infections and other diseases.

However, a blood routine test is only one indicator for examining disease. A completely normal blood routine test does not mean that there is no disease, and a slight problem in the blood routine test does not necessarily mean that there is a disease.

When seeing a doctor, we must first look at the person, and we must look at him comprehensively.