How to read the blood test report?

I went to the hospital for a cold and had my blood drawn.

Go for routine physical examination and blood draw.

In preparation for surgery, blood needs to be drawn.

…

Draw blood, draw blood, draw blood.

I wonder if you have the same feeling as Pang Ke. No matter what problems you have, you can’t do without blood tests when you go to the hospital. Why is there so much information hidden in the blood? And how do the dazzling numbers on the blood test report reflect our physical condition?

How does blood reflect the condition of the body?

Where does the blood in our bodies come from?

Blood is composed of blood cells and plasma.

Various blood cells, including white blood cells (neutrophils, eosinophils, basophils, monocytes, lymphocytes), red blood cells, and platelets, all originate from the common bone marrow hematopoietic stem cells. The production of these cells is extremely finely regulated by the hematopoietic microenvironment, cytokines, hematopoietic-related genes, etc., and different types and quantities of blood cells are differentiated from hematopoietic stem cells.

Plasma is the liquid component of blood, which is responsible for carrying blood cells, substances needed to maintain human activities and waste products produced by metabolism. Changes in the composition of plasma can reflect the body's metabolic activities and changes in the environment.

The number and function of blood cells and the various components dissolved in plasma will remain relatively constant. When organs and tissues are diseased, the blood will change to varying degrees. Measuring blood components can provide a basis for the diagnosis of the disease.

How to understand a “routine” blood test?

When it comes to the most common blood test, it must be the blood routine test. So how can we sort out the clues from a long list of items and understand this most "routine" blood routine test report?

This has to start with the three major components of a routine blood test: red blood cells, platelets and white blood cells.

Schematic diagram of oxygen transport by red blood cells

(Copyrighted image from the gallery, no permission to reprint)

The first is the largest number of red blood cells. Its existence not only makes our blood appear red, but its main component - hemoglobin also undertakes the most important "mission" of blood: carrying oxygen, so that oxygen can be transported to various organs throughout the body through blood flow.

Red blood cell count

Male: 4.0-5.50×1012/L

Female: 3.5-5.0×1012/L

Newborn: 6.0-7.0 × 1012/L

Hemoglobin concentration

Male: 120-160 g/L

Female: 110-150 g/L

Neonates: 170-200 g/L

When the red blood cell count and hemoglobin concentration are lower than normal, it means that the patient may have anemia, usually with symptoms such as hypoxia and pale complexion. Next, it is necessary to combine other items to further diagnose the pathogenesis and cause of anemia.

Mean corpuscular volume

Male: 80-100 FL

Female: 80-100 FL

Neonates: 97-109 FL

Anemia with red blood cell volume larger than normal is called macrocytic anemia, which is common in folic acid and vitamin B12 deficiency; anemia with small red blood cell volume is common in iron deficiency anemia; and anemia with normal red blood cell volume is usually caused by acute blood loss or abnormalities in the hematopoietic system. A blood test can determine whether anemia is present, but it cannot identify the cause of anemia, and other blood tests or even further examination and testing of the bone marrow are often required.

The second is platelets, which are formed by fragments shed by megakaryocytes in the bone marrow. Its main function is to stop bleeding.

Platelet count

125-350×109/L

If the platelet count in the test report is lower than normal, it means that the human body may be at risk of bleeding. If there is a long-term unprovoked thrombocytosis, attention should be paid to screening for tumor diseases.

As for white blood cells, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils (the so-called five-category classification), due to its large family, the results related to it often occupy half of the entire examination list.

White blood cells mainly play an immune function, so the number and proportion of white blood cells can often reflect whether the human body is infected.

Functions of white blood cells

White blood cell count

3.5-9.5×109/L

Monocytes

The reference count range is 0.3-0.8×109/L, and the reference ratio is 3-10%.

Neutrophils

The reference count range is 2.0-7.5×109/L, and the reference ratio is 50-70%.

Lymphocytes

The reference count range is 0.8-4.0×109/L, and the reference ratio is 17-50%.

Eosinophils

The reference count range is 0.02-0.52×109/L, and the reference ratio is 0.4-8.0%.

Basophils

The reference count range is 0.00-0.06×109/L, and the reference ratio is 0.0-1.0%.

Different types of white blood cells have different divisions of labor. When the number and proportion of neutrophils increase, it often means that the human body is under stress or has a bacterial infection. Viral invasion often leads to an increase in lymphocytes. When there is a parasitic infection or allergy, the number of eosinophils will increase...

This is why we need to do a routine blood test when we have a cold. If the number of lymphocytes on the test report is high, but the number and proportion of neutrophils are normal, it indicates that we should consider whether to put down the antibiotics in our hands and take antiviral drugs instead.

It should be noted that some infections not only do not cause leukocytosis, but instead lead to a decrease in leukocytosis. For example, HIV may cause lymphocytopenia, and severe bacterial infections and special infections such as typhoid fever may cause granulocytopenia.

In addition to reactive changes in white blood cell count, abnormal hematopoietic function or tumor diseases may also cause changes in white blood cell count. Therefore, we need to pay attention to abnormal values ​​to avoid missed diagnosis and misdiagnosis.

Routine blood tests can help doctors quickly make a comprehensive judgment on the patient's physical condition and are the most commonly used auxiliary examination method for diagnosing diseases. Therefore, understanding the routine blood test report is also a necessary task for every doctor.

What other diseases are related to blood?

In addition to routine blood tests, various components of plasma can also be detected through biochemical experimental methods. For example, the common "liver function" and "kidney function" tests show the basic status of organ function through various indicators related to the functional metabolism of organs such as the liver and kidneys. This is an important reference for judging organ function.

Blood biochemistry test sheet

Source: Science Popularization China

Unlike routine blood tests that specifically check blood cells, blood biochemistry tests "target" the plasma part of the blood.

In blood biochemical tests, the levels of various enzymes and albumin can reflect the state of liver function, while indicators such as creatinine, urea and electrolytes can indicate the health of the kidneys, help people judge their health status, and lock in the scope of the disease as quickly as possible.

With the development of science, many complex diseases can also be analyzed and identified through blood tests.

Take cancer, which everyone is afraid of, as an example. Generally speaking, if we want to conduct routine cancer screening during physical examinations, we need to undergo a series of auxiliary examinations such as B-ultrasound, MRI, endoscopy, CT, etc. The names alone are dizzying, not to mention that sometimes adjustments need to be made according to different types of cancer.

If a person without a professional medical background is asked to make a choice on his own, it will be difficult for him to choose the most suitable examination item without taking a "detour".

If someone told you at this time that you only need to have a blood test to screen whether there is a risk of cancer in our body, would you think it is a fantasy?

In fact, many medical examination institutions have long used blood, urine and other samples to test tumor markers such as carcinoembryonic antigen to determine whether the subject has cancer. However, due to the high rate of false positives and false negatives in tumor marker tests, tumor markers are not a reliable standard for cancer screening in authoritative medical guidelines.

There is now a view that ruptured tumor cells will release DNA fragments into the blood circulation system. If the DNA fragments belonging to tumor cells in the blood can be detected in time, the presence of cancer in the body can be detected before the tumor is formed.

Not only that, according to the research results published by Northwestern University School of Medicine, the detection of RNA markers in the blood can also be used to determine whether the subject suffers from depression. At present, the diagnosis of depression is mainly based on the subjective judgment of doctors, and this research result may provide an objective scientific basis for the diagnosis of depression in the future.

Blood is like a red river flowing in our body, complex and fascinating. Pang Ke also hopes that scientists can conduct more in-depth research to reveal more mysteries related to blood to us.

Do you know any other diseases that can be screened and diagnosed through blood tests? Please leave a message in the comment section. If there is a chance, we will continue to talk to you about things related to blood tests in subsequent sharing!

Creative team: China Science and Technology Museum New Media Team

Review expert: Jin Tao, chief physician of the Department of Hematology, Shenyang Red Cross Hospital