Understanding Erythropoiesis

*Please note: This slide show represents a visual interpretation and is not intended to provide, nor substitute as, medical and/or clinical advice.

What is erythropoiesis?

Erythropoiesis is the scientific term for the production of red blood cells. These cells, called erythrocytes, carry oxygen around the body. They develop from cells in the bone marrow called stem cells.¹

What are erythrocytes and why are they important?

Erythrocytes are extremely important to your health. They carry almost all the oxygen your body uses and make up almost half your blood.

What are erythrocytes and why are they important?

Eight out of 10 cells in your body are red blood cells.

What are erythrocytes and why are they important?

Red blood cells can be collected, stored and given to people who need them in a lifesaving procedure called a blood transfusion.

How erythrocytes develop

Let's look more closely at the life cycle of an erythrocyte.

Bone marrow is the tissue in your bones that is the factory for producing blood cells. First, it creates stem cells. These stem cells can then develop into more specialized cells called common myeloid progenitors (CMP) that have the ability to mature into all of the different blood cell types, including red blood cells called erythrocytes, white blood cells called leukocytes, and finally, platelets.

You already know that red blood cells carry oxygen around the body. White blood cells fight infection and platelets help stop bleeding after an injury.

The erythrocyte life cycle

The life cycle of a healthy erythrocyte is about 3-4 months. First, a stem cell commits to becoming a red blood cell and turns into a cell called an erythroblast. The erythroblast becomes a more developed blood cell called a reticulocyte and enters the bloodstream.

The erythrocyte life cycle

It takes about a week for a healthy reticulocyte to become a mature red blood cell. It then stays in your bloodstream until it naturally wears out and the body recycles it. Your bone marrow factory constantly replaces your supply of erythrocytes and other blood cells.²

Healthy red blood cells start in the bone marrow

The development of healthy, functioning erythrocytes depends on healthy stem cells in the bone marrow. If the bone marrow is not healthy, it produces defective stem cells. These cells may not be able to develop normally into blood cells. As a result, they may die in the bone marrow by a cellular process called apoptosis or programmed cell death. Apoptosis is one of the body's ways of removing damaged or defective cells.³

What is anemia?

There are many ways erythropoiesis can go wrong. When this occurs, the body does not have enough healthy red blood cells to carry oxygen around the body. This causes a condition called anemia. Your doctor might say you have a "low red cell count".

Symptoms of anemia

Symptoms of anemia include fatigue, difficulty getting your breath, and feeling like your heart is skipping beats. You might feel cold or have trouble climbing stairs or doing other activities that take some effort.

Finding the cause of symptoms

Your doctor will take a blood sample and do a variety of tests, including one called a complete blood count. They will check for a number of diseases that can cause low blood counts, including liver or kidney problems, a lack of vitamins, heart problems and some cancers.

When is my erythrocyte count low?

Men and women have different amounts of red blood cells in their body. Doctors measure the number of red cells indirectly by measuring the hemoglobin, which is the protein that carries oxygen in the body, or the hematocrit, the amount red blood cells take up of the total volume of blood.⁴

When is my erythrocyte count low?

Typical normal hemoglobin levels in men are 13.5-17.5 grams per deciliter. For women, a normal level is 12-15.5 grams per deciliter. In men, normal hematocrit levels range between 41 and 50 percent, while in women the normal hematocrit range is 36 to 48 percent.⁵

Treating a low erythrocyte count

You may need medication if your erythrocyte or red blood cell count is low. This is can be a shot, or injection, of medication to help your body make more healthy red blood cells.

Treating a low erythrocyte count

If the count drops too low, you might need a blood transfusion. This means getting fresh red cells through an IV.

Stem cell transplant

Finally, you may benefit from a stem cell transplant. This procedure is a way to replace damaged or diseased stem cells. The replacement of defective stem cells with healthy ones will restart the bone marrow and production of adequate numbers of functioning blood cells, including red blood cells.

References

1. Pelley JW. Amino acid and heme metabolism. In: Elsevier’s Integrated Biochemistry. Mosby; 2006:97-105.
2. Young K, Wise JA, DeSaiz P, et al. Erythrocytes. In: Anatomy and Physiology by OpenStax. XanEdu Publishing Inc; 2013. Accessed November 2, 2020. https://openstax.org/books/anatomy-and-physiology/pages/18-3-erythrocytes
3. Harvey JW. Chapter 7: The erythrocyte: Physiology, metabolism, and biochemical disorders. In: Kaneko J, Harvey JW, Bruss M, eds. Clinical Biochemistry of Domestic Animals (6th ed.) Academic Press;2008:173-240. https://www.researchgate.net/publication/38285674_Clinical_Biochemistry_of_Domestic_Animals
4. Understanding blood counts. Leukemia & Lymphoma Society website. Accessed November 3, 2020. https://www.lls.org/managing-your-cancer/lab-and-imaging-tests/understanding-blood-counts
5. www.redcrossblood.org/donate-blood/dlp/hematocrit.html