Anemia is not just "blood deficiency"! Learn more about the classification, causes and diagnosis of anemia

Author: Wang Xuejing, Chief Physician of Civil Aviation General Hospital

Reviewer: Wang Lixiang, Chief Physician, Third Medical Center, PLA General Hospital

The 10th Chairman of the Science Popularization Branch of the Chinese Medical Association

Anemia is a common blood disease, which is defined as the hemoglobin (commonly known as hemoglobin) content in the blood being lower than the normal range, resulting in a decrease in oxygen transport capacity, affecting the metabolism and function of tissues and organs throughout the body. Common symptoms include pale face, fatigue, drowsiness, fear of cold, rapid heart rate, etc. In severe cases, it can also increase the burden on the heart.

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There are various ways to classify anemia. According to the speed of onset, it can be divided into acute and chronic anemia; according to the cause, it can be subdivided into various types such as hematopoietic substance deficiency, hematopoietic dysfunction, and imbalance between blood supply and demand; according to the severity, there are mild, moderate, severe and extremely severe. Acute anemia is usually caused by acute blood loss, such as massive bleeding caused by trauma, surgery or traffic accidents, as well as rare acute hemolytic events. The causes of chronic anemia are more complicated, including but not limited to long-term factors such as menstrual blood loss, malnutrition, tumors, chronic inflammation or infection. In specific populations, such as pregnant women and children, due to increased physiological needs, they are more likely to suffer from anemia caused by insufficient hematopoietic essential substances such as iron, folic acid or vitamin B12.

From the perspective of etiology, the lack of hematopoietic substances is one of the most common causes of anemia. For example, iron is one of the key components for the synthesis of hemoglobin. Iron deficiency will lead to a decrease in hemoglobin in red blood cells, resulting in a decrease in volume, forming the so-called "microcytic hypochromic anemia". Folic acid and vitamin B12 are essential for DNA synthesis. Their deficiency will cause red blood cells to develop but not divide, so the cell volume increases, forming "megaloblastic anemia". In addition, in some cases, despite sufficient iron content in the body, anemia can also occur due to iron utilization disorders (such as sideroblastic anemia). Bone marrow is the main site for red blood cell production, and impaired function can also cause anemia. For example, leukemia, drugs, etc. can directly destroy or inhibit the hematopoietic function of the bone marrow.

For individuals suspected of anemia, doctors usually recommend a series of tests to confirm the diagnosis. First of all, a complete blood count is the most basic and important test item, which can provide key information such as the number of red blood cells, hemoglobin concentration, and red blood cell volume. Among them, the hemoglobin level is the direct basis for judging the presence and severity of anemia. According to my country's standards, adult male hemoglobin levels below 120g/L and adult female hemoglobin levels below 110g/L are considered anemia.

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Furthermore, parameters such as mean corpuscular volume (MCV), mean corpuscular hemoglobin content (MCH) and mean corpuscular hemoglobin concentration (MCHC) can help doctors analyze the specific type of anemia. For example, patients with iron deficiency anemia have low MCV, MCH and MCHC, while patients with megaloblastic anemia have high MCV and MCH, but not necessarily MCHC.

In addition to basic blood tests, in order to explore the root cause of anemia, doctors may also ask patients to undergo more detailed tests, such as serum iron, ferritin, transferrin saturation, soluble transferrin receptor, folic acid and vitamin B12 levels. Serum iron reflects the amount of available iron in the body, and ferritin is an important indicator of iron reserves. Its level often decreases earlier than the onset of anemia symptoms, indicating that there may be a risk of iron deficiency. In another case, the body is not lacking in iron but cannot use iron. At this time, the ferritin level will increase, such as sideroblastic anemia. It is worth noting that ferritin levels may also increase in anemia caused by some chronic diseases, such as chronic inflammation, tumors, etc. Therefore, a comprehensive judgment should be made based on clinical manifestations and other laboratory data.

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Anemia during pregnancy is an issue that deserves attention. As the fetus grows, the mother needs to produce more red blood cells to support the metabolic needs of the fetus and herself. This process significantly increases the demand for iron. If sufficient iron is not supplemented in time, anemia is very likely to occur, which in turn affects the healthy development of the fetus. Studies have shown that anemia during pregnancy is not only associated with problems such as low birth weight and premature birth of newborns, but may also affect the cognitive development of the baby. Therefore, regular monitoring of the hemoglobin level of pregnant women and giving appropriate iron, folic acid and vitamin supplements as needed are important measures to prevent anemia during pregnancy.