Teach you how to read blood routine

Author: Chen Zhou, Department of Nephrology, Shanghai Changhai Hospital

Reviewer: Mei Xiaobin, Chief Physician, Nephrology Department, Shanghai Changhai Hospital

Figure 1 Copyright image, no permission to reprint

Blood routine test is a common examination item, which can reflect our blood condition and physical health. However, many people do not know how to understand the various indicators and symbols on the blood routine test report after receiving it, and even have unnecessary worries because of some normal fluctuations.

What is a blood test?

A blood test, also called a complete blood count (CBC), is a test that measures the number and proportion of various cells in our blood. It can help us diagnose and monitor some diseases, such as anemia, infection, bleeding, cancer, etc.

What can a routine blood test detect?

Routine blood tests can mainly detect three types of blood cells: red blood cells, white blood cells and platelets. Each type of blood cell has its own function and characteristics, as well as its own normal reference range and possible causes of abnormal changes. Let's introduce these three types of blood cells separately.

Red blood cells

Red blood cells (RBCs), also called erythrocytes or red corpuscles, are the most numerous type of cells in our blood. Their main function is to carry oxygen (O2) and carbon dioxide (CO2) to provide energy to our bodies and remove waste.

The quantity and quality of red blood cells can reflect our oxygen delivery capacity and hematopoietic function. If there are too many or too few red blood cells, or if the shape, size, color, etc. of red blood cells are abnormal, some diseases or symptoms may occur.

The indicators of red blood cells in a routine blood test include: red blood cell count, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and red blood cell distribution width. Isn't it a bit confusing? In fact, you only need to look at the hemoglobin item.

Hemoglobin

Hemoglobin is a protein in red blood cells that can combine with oxygen to form oxyhemoglobin, or combine with carbon dioxide to form carboxyhemoglobin. The normal reference range also varies according to gender and age. Generally speaking, it is 120-160 g/L for adult males and 110-150 g/L for adult females.

leukocyte

White blood cells (WBC), also known as leukocytes, their main function is to participate in our immune system and protect us from foreign pathogens (such as bacteria, viruses, parasites, etc.) and internal abnormal cells (such as cancer cells, autoimmune diseases, etc.).

The number and type of white blood cells can reflect our immune status and inflammatory response. If there are too many or too few white blood cells, or if the ratio or shape of white blood cells is abnormal, some diseases or symptoms may occur.

The indicators of white blood cells in a routine blood test include the following: white blood cell count, neutrophil count, lymphocyte count, monocyte count, eosinophil count, and basophil count. Among them, the focus is on the white blood cell count and the neutrophil ratio.

White blood cell count and neutrophil ratio

The normal white blood cell count (WBC) for adults is 4.0 to 10.0×109/L. Leukocytosis often indicates infection. You can also further check whether the neutrophil ratio is increased (normal value is 50% to 70%) to exclude the possibility of acute and suppurative infection. For patients with kidney disease, if they take oral hormones or immunosuppressants, they are very likely to get infected, so the white blood cell count and neutrophil ratio also need to be paid special attention.

Figure 2 Copyright image, no permission to reprint

Platelets

The main function of platelets (PLT) is to participate in our coagulation system and protect us from the harm of bleeding.

The number and activity of platelets can reflect our ability to bleed and stop bleeding. If there are too many or too few platelets, or if the function of platelets is abnormal, some diseases or symptoms may occur.

We focus on platelet count : platelets can produce a variety of platelet factors and participate in blood coagulation. They are also a type of immune cell that participates in the body's immune response. The normal value for men is (100-300)×109/L, and for women it is (101-320)×109/L. Clinically, patients with cirrhosis and hypersplenism can cause excessive platelet destruction, which can lead to thrombocytopenia. In addition, many drugs can also cause thrombocytopenia, such as aspirin and heparin sodium.

Iron metabolism index

Patients with chronic kidney disease are prone to anemia. In addition to looking at hemoglobin, the focus should be on two iron metabolism indicators, ferritin (SF) and transferrin saturation (TSAT), to see if there is a deficiency of iron, the raw material for hematopoiesis.

For non-dialysis chronic kidney disease patients, if TSAT ≤ 20%, SF ≤ 100 μg/L; for hemodialysis patients, if TSAT ≤ 20%, SF ≤ 200 μg/L, it indicates insufficient iron stores and iron supplementation is needed to improve anemia.