From the Guidelines
Low red blood cell (RBC) count, also known as anemia, is most commonly caused by iron deficiency, followed by vitamin B12 or folate deficiency, and can also be due to blood loss, bone marrow disorders, chronic diseases, hemolysis, or certain medications. According to the most recent and highest quality study 1, the causes of anemia can be classified based on the mean corpuscular volume (MCV) into microcytic, normocytic, and macrocytic anemia. Microcytic anemia is most commonly caused by iron deficiency, while normocytic anemia may be caused by hemorrhage, hemolysis, or bone marrow failure. Macrocytic anemia is often megaloblastic, indicating vitamin B12 or folate deficiency.
The kinetic approach to evaluating anemia focuses on the underlying mechanism, distinguishing among production, destruction, and loss of RBCs 1. A low reticulocyte index (RI) indicates decreased RBC production, suggesting iron deficiency, vitamin B12/folate deficiency, or bone marrow dysfunction. On the other hand, a high RI suggests normal or increased RBC production, indicating blood loss or hemolysis.
Some common causes of anemia include:
- Nutritional deficiencies, particularly iron, vitamin B12, and folate
- Blood loss from trauma, surgery, heavy menstruation, or gastrointestinal bleeding
- Bone marrow disorders like leukemia, myelodysplastic syndrome, or aplastic anemia
- Chronic diseases such as kidney disease, rheumatoid arthritis, and cancer
- Hemolysis, the premature destruction of red blood cells, occurs in conditions like sickle cell disease, thalassemia, and autoimmune hemolytic anemia
- Certain medications, including chemotherapy drugs, some antibiotics, and immunosuppressants
Treatment depends on identifying and addressing the underlying cause, which may include iron supplements, vitamin supplementation, blood transfusions, or medication adjustments 1. Anyone experiencing symptoms like fatigue, weakness, dizziness, or shortness of breath should seek medical evaluation to determine the specific cause of their low RBC count.
From the Research
Causes of Low Red Blood Cell Count
The causes of low red blood cell (RBC) count, also known as anemia, can be attributed to various factors. Some of the main causes include:
- Nutritional deficiencies, such as lack of iron, vitamin B12, and folate 2, 3
- Ineffective erythropoiesis, which is the process of producing new RBCs 3
- Iron deficiency, which can lead to reduced hemoglobin synthesis and smaller, less hemoglobinized RBCs 3, 4
- Vitamin B12 and folate deficiencies, which can inhibit purine and thymidylate syntheses, impair DNA synthesis, and cause erythroblast apoptosis 3, 5
- Combined deficiencies, such as iron and vitamin B12 or folate deficiencies, which can mask the symptoms of megaloblastic anemia 6
Role of Iron, Vitamin B12, and Folate
Iron, vitamin B12, and folate play crucial roles in the production of RBCs. Iron is necessary for hemoglobin synthesis, while vitamin B12 and folate are required for DNA synthesis and cell proliferation 3. Deficiencies in these nutrients can lead to anemia, which can cause symptoms such as weakness, lethargy, palpitations, headache, and shortness of breath 2.
Diagnosis and Treatment
Diagnosing the cause of low RBC count is essential for effective treatment. Laboratory tests, such as full blood count and measurement of iron, vitamin B12, and folate levels, can help identify the underlying cause of anemia 2, 6. Treatment may involve supplementation with iron, vitamin B12, and folate, as well as addressing any underlying conditions that may be contributing to the deficiency 5, 4.