The red blood cell (RBC) count is a test that measures the number of oxygen-carrying blood cells in your blood. An abnormal RBC test result is often the first sign of an illness. The test requires a simple blood sample.
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Normal RBC Reference Range
An RBC count is the number of red blood cells per a particular volume of blood. It may be reported in millions of cells per microliter (mcL) of blood or in trillions of cells per liter (L) of blood.
Anything above or below these RBC levels may point to a condition. However, keep in mind that other factors can influence normal results.
If you live in a high-altitude city like Denver, for example, your blood count will be different than those of people who live in low-altitude areas like the Gulf Coast.For this reason, the ranges cannot be considered hard-and-fast values but just reference points.
RBCs and a Complete Blood CountA test for red blood cell (RBC) count is often part of acomplete blood count(CBC) test. In addition to RBCs, this test measures:Hemoglobin(Hb), the protein in RBCs that carries oxygen and carbon dioxide moleculesWhite blood cells(WBC), which are a part of the immune systemPlatelets (PLT), the cells responsible for blood clottingHematocrit(Hct), the ratio of RBCs to the total volume of bloodIt’s common to take up to a few days before your provider receives the results and shares them with you.
RBCs and a Complete Blood Count
A test for red blood cell (RBC) count is often part of acomplete blood count(CBC) test. In addition to RBCs, this test measures:Hemoglobin(Hb), the protein in RBCs that carries oxygen and carbon dioxide moleculesWhite blood cells(WBC), which are a part of the immune systemPlatelets (PLT), the cells responsible for blood clottingHematocrit(Hct), the ratio of RBCs to the total volume of bloodIt’s common to take up to a few days before your provider receives the results and shares them with you.
A test for red blood cell (RBC) count is often part of acomplete blood count(CBC) test. In addition to RBCs, this test measures:
It’s common to take up to a few days before your provider receives the results and shares them with you.
Complete Blood Count (CBC) Analyzer: Decode Your Results
High Red Blood Cell Count
A high red blood cell count is callederythrocytosis.It can lead to symptoms of an enlarged spleen, blood clots, and other impacts. Symptoms that can occur with high RBC levels can depend on the cause and include:
High RBC levels can be due to either a primary cause (a condition) or a secondary one such as a medication or co-occurring disease that is preventing the body from receiving enough oxygen.Some of these causes include:
In other cases, factors like high altitude, smoking, or carbon monoxide poisoning may be the cause.
Cancer and High RBCsCancers associated with high RBC results include:Kidney cancerLiver cancerPolycythemia vera, a rare type of blood cancer
Cancer and High RBCs
Cancers associated with high RBC results include:Kidney cancerLiver cancerPolycythemia vera, a rare type of blood cancer
Cancers associated with high RBC results include:
High RBC Count Treatment
Treatment of an abnormal RBC count is typically focused on addressing the underlying condition. These treatments will vary widely depending on the cause, but there are steps you can take to improve your RBC count. If you need to lower your RBC count, you can:
Low Red Blood Cell Count
A low RBC count shows there is a decrease in oxygen-carrying cells in the blood. This is calledanemia. A low RBC count can indicate a serious problem, but not always.
If left untreated, anemia can lead to life-threatening complications. Various infections, nutritional deficiencies, and medical conditions may cause anemia. Some of these include:
A low RBC count isn’t always serious. For example, your RBC count may be low if you are pregnant or menstruating, or if you aren’t getting enough iron in your diet. If you do have a low RBC count, however, you may need tests to rule out more serious causes.
Low RBC Risk FactorsCertain people may be more likely to experience low RBC levels, including:Older people and young childrenPeople taking certain medications (proton pump inhibitors that lead to vitamin malabsorption, for example)People with inadequate diets, including strictvegan dietsPregnant peoplePeople with an underlying inflammatory condition (lupus,inflammatory bowel disease)
Low RBC Risk Factors
Certain people may be more likely to experience low RBC levels, including:Older people and young childrenPeople taking certain medications (proton pump inhibitors that lead to vitamin malabsorption, for example)People with inadequate diets, including strictvegan dietsPregnant peoplePeople with an underlying inflammatory condition (lupus,inflammatory bowel disease)
Certain people may be more likely to experience low RBC levels, including:
Low RBC Count Treatment
It’s important to treat any underlying conditions that contribute to the anemia. For example, take yourthyroid medicationsas prescribed if you have thyroid problems.
Summary
A red blood cell count is used to measure the number of oxygen-carrying red blood cells in your body. When you have a high blood count or a low blood count, it’s a sign that you may be sick.
9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Newhall DA, Oliver R, Lugthart S.Anaemia: A disease or symptom.Neth J Med. 2020 Apr;78(3):104-110. PMID:32332184Leukemia & Lymphoma Society.Understanding blood counts.Akunov A, Sydykov A, Toktash T, Doolotova A, Sarybaev A.Hemoglobin changes after long-term intermittent work at high altitude.Front Physiol. 2018;9:1552. doi:10.3389/fphys.2018.01552MedlinePlus.Blood count tests.Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi:10.1503/cmaj.191587Cavalca F, Aroldi A, Ripamonti A, Ferrari S, Palamini S, Mottadelli F,et al.Idiopathic erythrocytosis: a germline disease?Clin Exp Med. 2024 Jan 20;24(1):11. doi:10.1007/s10238-023-01283-yMalenica M, Prnjavorac B, Bego T, et al.Effect of cigarette smoking on haematological parameters in healthy population.Med Arch. 2017;71(2):132-136. doi:10.5455/medarh.2017.71.132-136Penn Medicine.What Is Anemia?National Heart, Blood, and Lung Institute.Iron-deficiency anemia.Additional ReadingAmerican Association for Clinical Chemistry/Lab Tests Online.Red blood cell count (RBC).
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Newhall DA, Oliver R, Lugthart S.Anaemia: A disease or symptom.Neth J Med. 2020 Apr;78(3):104-110. PMID:32332184Leukemia & Lymphoma Society.Understanding blood counts.Akunov A, Sydykov A, Toktash T, Doolotova A, Sarybaev A.Hemoglobin changes after long-term intermittent work at high altitude.Front Physiol. 2018;9:1552. doi:10.3389/fphys.2018.01552MedlinePlus.Blood count tests.Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi:10.1503/cmaj.191587Cavalca F, Aroldi A, Ripamonti A, Ferrari S, Palamini S, Mottadelli F,et al.Idiopathic erythrocytosis: a germline disease?Clin Exp Med. 2024 Jan 20;24(1):11. doi:10.1007/s10238-023-01283-yMalenica M, Prnjavorac B, Bego T, et al.Effect of cigarette smoking on haematological parameters in healthy population.Med Arch. 2017;71(2):132-136. doi:10.5455/medarh.2017.71.132-136Penn Medicine.What Is Anemia?National Heart, Blood, and Lung Institute.Iron-deficiency anemia.Additional ReadingAmerican Association for Clinical Chemistry/Lab Tests Online.Red blood cell count (RBC).
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Newhall DA, Oliver R, Lugthart S.Anaemia: A disease or symptom.Neth J Med. 2020 Apr;78(3):104-110. PMID:32332184Leukemia & Lymphoma Society.Understanding blood counts.Akunov A, Sydykov A, Toktash T, Doolotova A, Sarybaev A.Hemoglobin changes after long-term intermittent work at high altitude.Front Physiol. 2018;9:1552. doi:10.3389/fphys.2018.01552MedlinePlus.Blood count tests.Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi:10.1503/cmaj.191587Cavalca F, Aroldi A, Ripamonti A, Ferrari S, Palamini S, Mottadelli F,et al.Idiopathic erythrocytosis: a germline disease?Clin Exp Med. 2024 Jan 20;24(1):11. doi:10.1007/s10238-023-01283-yMalenica M, Prnjavorac B, Bego T, et al.Effect of cigarette smoking on haematological parameters in healthy population.Med Arch. 2017;71(2):132-136. doi:10.5455/medarh.2017.71.132-136Penn Medicine.What Is Anemia?National Heart, Blood, and Lung Institute.Iron-deficiency anemia.
Newhall DA, Oliver R, Lugthart S.Anaemia: A disease or symptom.Neth J Med. 2020 Apr;78(3):104-110. PMID:32332184
Leukemia & Lymphoma Society.Understanding blood counts.
Akunov A, Sydykov A, Toktash T, Doolotova A, Sarybaev A.Hemoglobin changes after long-term intermittent work at high altitude.Front Physiol. 2018;9:1552. doi:10.3389/fphys.2018.01552
MedlinePlus.Blood count tests.
Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi:10.1503/cmaj.191587
Cavalca F, Aroldi A, Ripamonti A, Ferrari S, Palamini S, Mottadelli F,et al.Idiopathic erythrocytosis: a germline disease?Clin Exp Med. 2024 Jan 20;24(1):11. doi:10.1007/s10238-023-01283-y
Malenica M, Prnjavorac B, Bego T, et al.Effect of cigarette smoking on haematological parameters in healthy population.Med Arch. 2017;71(2):132-136. doi:10.5455/medarh.2017.71.132-136
Penn Medicine.What Is Anemia?
National Heart, Blood, and Lung Institute.Iron-deficiency anemia.
American Association for Clinical Chemistry/Lab Tests Online.Red blood cell count (RBC).
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