Low oxygen levels, misuse of certain drugs and blood cancers can cause a high red blood cell count.
Low oxygen levels
The body might make more red blood cells as a response to conditions that result in low oxygen levels. These might include:
- Congenital heart disease in adults
- COPD (chronic obstructive pulmonary disease) — the blanket term for a group of diseases that block airflow from the lungs — including emphysema.
- Heart failure
- Hemoglobinopathy, a condition present at birth that reduces red blood cells' ability to carry oxygen.
- Living at high altitudes.
- Pulmonary fibrosis — a disease that happens when lung tissue becomes damaged and scarred.
- Sleep apnea — a condition in which breathing stops and starts many times during sleep.
- Nicotine dependence (smoking)
In some people, cancers or pre-cancers that affect the bone marrow can cause too many red blood cells to form. An example is:
- Polycythemia vera
Misuse of drugs to improve athletic performance
Certain drugs boost the making of red blood cells, including:
- Anabolic steroids.
- Blood doping, also called transfusion.
- Shots of a protein known as erythropoietin.
Higher red blood cell concentration
If the liquid part of the blood, known as plasma, gets too low, the red blood cell count seems to go up. This happens in dehydration. However, the red blood cells are simply more tightly packed. The number of red blood cells stays the same.
Rarely, in some kidney cancers or after kidney transplant, the kidneys might produce too much of the hormone erythropoietin. This causes the body to make more red blood cells. Red blood cell counts also can be high in nonalcoholic fatty liver disease.
- Nonalcoholic fatty liver disease
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.
Feb. 10, 2023
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- Tefferi A. Diagnostic approach to the patient with polycythemia. https://www.uptodate.com/contents/search. Accessed Oct. 26, 2022.
- CBC with differential, blood. Mayo Medical Laboratories. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9109. Accessed Oct. 26, 2022.
- Weitz M, et al. Blood. In The Big Picture Physiology: Medical Course & Step 1 Review. 2nd ed. McGraw Hill; 2020. https://accessmedicine.mhmedical.com. Accessed Oct. 26, 2022.
- Walls RM, et al., eds. Anemia and polycythemia. In: Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Elsevier; 2023. http://www.clinicalkey.com. Accessed Oct. 26, 2022.
- Loscalzo J, et al. Anemia and polycythemia. In: Harrison's Principles of Internal Medicine. 21st ed. McGraw Hill; 2022. https://accessmedicine.mhmedical.com. Accessed Oct. 26, 2022.
- Zhong F, et al. Red blood cell count: An unrecognized risk factor for nonalcoholic fatty liver disease. Frontiers in Endocrinology. 2021; doi:10.3389/fendo.2021.760981.