A red blood cell (erythrocyte) count is a test used to measure the number of blood cells that carry oxygen in a volume of blood. It is one of the main tests that doctors use to determine the amount of oxygen that is transported to the cells of the body.
An abnormal red blood cell count is usually the first sign of disease. In other cases, the test can give the doctor a diagnosis if symptoms such as unexplained fatigue or shortness of breath develop.
Read on to learn more about your red blood cell count and what it means if it's too low or too high.
Complete blood count
In general, to diagnose a disease, the doctor must look not only at the number of red blood cells. This is most often done as part of a more comprehensive test called a complete blood count (CBC) . This test measures several different components of a blood sample, including:
- Red blood cells (erythrocytes) that carry oxygen to the cells of the body.
- Hemoglobin (Hb), a protein in red blood cells that carries oxygen and carbon dioxide molecules.
- White blood cells (WBC), which are part of the immune system.
- Platelets (PLT), the cells responsible for blood clotting.
- Hematocrit (Hct), the ratio of red blood cells to total blood volume
Based on the composition of the blood, doctors can better understand what to look for when trying to diagnose a disease.
Red blood cell counts can also be used to monitor treatments for blood disorders or to take medications that affect your red blood cells. This is especially true for cancer and chemotherapy. Both can negatively affect blood counts.
The red blood cell count is the number of red blood cells in a given volume of blood. It can be expressed in millions of cells per microliter (μl) of blood or in trillions of cells per liter (l) of blood.
The "normal" or "reference" range can sometimes vary depending on whose blood is being tested. If you live in a high-altitude city like Denver, your blood count will be much higher than that of people living in low-altitude areas like the Gulf Coast.
This is because when you are at higher altitudes, your body creates more red blood cells so that more oxygen can be delivered to your tissues. For this reason, the ranges should not be considered as exact values, but only as a guide.
The control range for the number of red blood cells depends on sex and age:
- Women: 4.2 to 5.4 million / μL
- Men: 4.7 to 6.1 million / μL
- Children: 4.1 to 5.5 million / μL.
High or low red blood cell count
When the red blood cell count is above or below the average range, it alerts the doctor that a medical condition may be the cause. Other CBC values will be discussed, as well as other diagnostic tests.
Causes of high red blood cell count
A high red blood cell count tells us that there is an increase in the number of oxygen-carrying cells in the blood. In some cases, this may indicate that the body is trying to compensate for a condition that is preventing the body from getting enough oxygen. In other cases, the cause may be related to medical conditions or medications that increase red blood cell production.
Some of these reasons include:
Causes of low red blood cell count
A low red blood cell count indicates a decrease in the number of oxygen-carrying cells in the blood. This is called anemia . Various infections, nutritional deficiencies, and illnesses can cause anemia. Some of these include:
- Renal insufficiency
- Thyroid problems
- Internal or external bleeding
- Leukemia , a type of white blood cell cancer.
- Side effects of medications, including chemotherapy
- Multiple myeloma is a type of cancer that affects plasma blood cells.
- Erythropoietin deficiency, a kidney hormone that promotes the growth of red blood cells.
- Lack of iron, folic acid, vitamin B12 , or vitamin B6.
- Hemolysis , abnormal breakdown of red blood cells.
- The pregnancy
Treatment for abnormal red blood cell counts is usually aimed at correcting the underlying condition. These treatments will vary widely depending on the cause.
But if the cause is a nutritional deficiency, medication, or a chronic illness, there are a few things you can do not only to improve your blood count, but to improve your overall health as well.
Treat a high red blood cell count
If you have a high red blood cell count:
- Exercise to improve heart and lung function.
- Eat less red meat and foods rich in iron.
- Avoid taking iron supplements.
- Stay well hydrated.
- Avoid diuretics , including coffee and caffeinated drinks, which can dehydrate you.
- Stop smoking, especially if you have COPD or pulmonary fibrosis .
- Avoid using steroids, erythropoietin, and other performance-enhancing medications.
Treat a low red blood cell count
If you have a low red blood cell count (including anemia):
The red blood cell count is used to measure the number of red blood cells that carry oxygen in your body. If you have a high or low blood count, this is a sign that you are sick.
Your doctor will also monitor your red blood cell count when you have a blood disorder or are taking medications that affect it. If you have an abnormal red blood cell count, your doctor will treat the condition that is causing the problem.