What Causes Your Red Blood Cells to Be Low?

Medically Reviewed on 6/28/2022
What Causes Your Red Blood Cells to Be Low?
A red blood cell (RBC) count measures the number of red blood cells, also called erythrocytes, in your blood.

Red blood cells (RBCs) are the most common type of cells found in the bloodstream. It is the abundance of these cells that give the blood its color.

The main function of a red blood cell is to carry oxygen and transfer it throughout the body. To achieve this, the cells contain a protein in them called hemoglobin. This protein helps carry the oxygen molecule around the body because hemoglobin contains iron inside it. The iron helps hold the oxygen within the cell and gives the cell its red color.

All these factors combined allow the RBCs to transport oxygen in the body. The amount of oxygen your body receives is directly proportional to the number of red cells your body has.

5 causes for a low red blood cell count

  1. Iron deficiency anemia: The most common cause of low red blood cells is anemia due to iron deficiency. This can be caused by losing a lot of blood, a decrease in iron absorption from food by the body, reduced iron intake via your diet, malnutrition, etc. Pregnancy can lead to anemia due to the increase in demand for iron supply to the fetus.
  2. Other types of anemia: A low red cell count could arise from other types of anemia, such as chronic diseases (diabetes or cancer), autoimmune hemolytic anemia, and aplastic anemia.
  3. Hemolysis: The breakdown or destruction of red blood cells is called hemolysis. Hemolysis can be caused by an autoimmune reaction to a blood transfusion, infection, or genetic diseases, such as sickle cell anemia.
  4. Treatments: In cancer patients, chemotherapy or radiation therapy can cause mass destruction of red blood cells. The process involves strong chemicals and radiations that can be harmful to blood cells, thereby diminishing them.
  5. Heavy menstruation: People who experience heavy period flow regularly may tend to have a low red blood cell count. If they do not compensate for the loss adequately through their diet, their blood count is reduced and does not get replenished, leading to a low red blood cell count.


Anemia: Common Causes, Symptoms, Types, and Treatment See Slideshow

Red blood cell count

A red blood cell (RBC) count measures the number of red blood cells, also called erythrocytes, in your blood. A greater or lower than usual RBC count is frequently the first indicator of anemia. As a result, the test may enable you to receive therapy much before you experience any symptoms.

A red blood cell (RBC) count is often part of a complete blood count, which is a collection of tests that assesses several aspects of your blood. The RBC measurement aids in the diagnosis of red blood cell diseases, most commonly, anemia.

A woman's red blood cell counts are typically lower than a man’s, and the number of red blood cells decreases with age. In a healthy individual, the normal range of RBCs are:

  • Women: 4.2 to 5.4 million cells/mcL.
  • Men: 4.7 to 6.1 million cells/mcL.

Low red blood cell count

Any values considerably lower than the normal range are considered a low red blood cell (RBC) count. If your cell count is much lower than 4.2 million cells/mcL, then you may have anemia. Anemia is a medical condition characterized by a low blood cell count, hence low oxygen levels in the body. This condition could be fatal if not treated sooner.

There can be other factors that cause low blood cell count. Vitamin B6, B12, or folate deficiency could be the cause of a low RBC count. Internal bleeding, kidney illness, and malnutrition (when the diet lacks sufficient nutrients to meet the body's demands) are other possibilities.

8 symptoms of low red blood cell count

  1. Weakness
  2. Tiredness, fatigue
  3. Shortness of breath
  4. Lightheadedness, dizziness
  5. Increased heart rate
  6. Difficulty being active during the day
  7. Difficulty performing tasks, such as climbing stairs and lifting objects
  8. Poor focus or concentration
Medically Reviewed on 6/28/2022
Image Source: iStock image

American Cancer Society. Low Red Blood Cell Counts (Anemia). https://amp.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/low-blood-counts/anemia.html

Medline Plus. Red Blood Cell (RBC) Count. https://medlineplus.gov/lab-tests/red-blood-cell-rbc-count/