What causes anemia?

Anemia is a common blood disorder, primarily characterized by hemoglobin concentration or red blood cell count below the normal range. It can be mainly classified into the following categories:

1. Malnutrition: Long-term unbalanced diet, especially deficiency in essential nutrients for blood cell production such as iron, folic acid, and vitamin B12. These two vitamins are crucial for red blood cell production. Their deficiency can lead to megaloblastic anemia, characterized by enlarged red blood cells but reduced in number.

2. Excessive red blood cell destruction: This mainly occurs in hemolytic anemia, where red blood cells are destroyed prematurely in the body, exceeding the compensatory capacity of the bone marrow.

3. Excessive blood loss: Trauma, surgery, chronic blood loss disorders, or excessive menstrual bleeding in women can all lead to hemorrhagic anemia. Blood loss reduces the circulating blood volume, thereby causing anemia.

4. Abnormal bone marrow hematopoietic function: The bone marrow is the primary site for red blood cell production. Diseases of the bone marrow (such as aplastic anemia) or infiltration of bone marrow by malignant tumors can all cause anemia.

5. Genetic factors: Certain inherited disorders, such as thalassemia and sickle cell anemia, can affect the structure of hemoglobin or the lifespan of red blood cells, thus causing anemia.

6. Chronic diseases: Long-term inflammation, kidney disease, cancer, and other chronic conditions can affect red blood cell production through various mechanisms, leading to anemia.

In summary, the causes of anemia are complex and varied, and diagnosis and treatment should be based on the patient's specific condition.