If you look at the red blood cell count on a complete blood count (CBC), you can see several different initials included along with the total. Red blood cell indices, called MCHC, MCV, MCH, and RDW, provide additional information about your red blood cells and can be helpful in determining the cause of anemia and other medical conditions .
Let's take a look at the information on your CBC , including your red blood cell count, and then take a look at the meaning and importance of each of these metrics.
Complete blood count
A complete blood count (CBC) is a blood test ordered by your healthcare provider to evaluate the composition and quality of the blood cells in your body. These blood cells include:
- White blood cells (white blood cells) that help fight infection.
- Red blood cells (erythrocytes) that distribute oxygen throughout the body.
- Platelets (platelets) that clot the blood.
Erythrocyte count (erythrocytes)
The red blood cell count (RBC) is the number of red blood cells in your blood. It is measured in millions of cells per microliter (μl).
The normal red blood cell count depends on age and gender :
- Women : 4.2 – 5.4 million / microliter
- Men : 4.7 – 6.1 million / μL
- Children : 4.1 – 5.5 million / μL
A low red blood cell count is called anemia . There are many different causes of anemia, of which iron deficiency is only one. Red blood cell indices are very helpful in distinguishing between these various causes .
An increased number of red blood cells is called erythrocytosis or polycythemia . The reasons may include:
- Dehydration, in which the number of red blood cells is actually small, but occurs because there is less fluid in the blood.
- The need for more oxygen in the blood, such as living high up, chronic obstructive pulmonary disease, or heart failure.
- Increased production of red blood cells in the bone marrow due to conditions such as polycythemia vera.
While the total red blood cell count can tell you if your red blood cell count is low, normal, or high, it does not tell you why the count is abnormal. Hence the need for further evaluation of these cells. Even if the red blood cell count is normal, viewing the red blood cell indices can sometimes provide important clues when diagnosing disease.
Red blood cell counts
Along with the total red blood cell count, the red blood cell indices provide information about the size and quality of your red blood cells. This can be used to diagnose the cause and severity of anemia and provide important information about other conditions you may have .
Red blood cell indices are made up of four different components known as mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red blood cell distribution width (RDW) .
Mean corpuscular hemoglobin concentration (MCHC)
Hemoglobin is an iron-transporting protein in red blood cells whose function is to transport oxygen. It is also the element that gives color to red blood cells. Any change in concentration can make cells more or less red.
Basically, the MCHC tells you if a person's red blood cells have more or less hemoglobin than you would expect. The normal range of MCHC for adults is 32 to 36 grams per deciliter. Any out of range value is defined as follows:
When the MCHC is high, the red blood cells are said to be hyperchromic . Possible causes of a high MCHC (which is rare) include :
- Autoimmune hemolytic anemia , a condition in which the body's immune system attacks its own red blood cells.
- Hereditary spherocytosis is a genetic disorder characterized by anemia and gallstones.
When the MCHC is low, the cells are said to be hypochromic . Possible causes include iron deficiency anemia . Several conditions can cause iron deficiency anemia, including pregnancy, blood loss, poor intestinal absorption of iron (caused, for example, by celiac disease or Crohn's disease ), and insufficient dietary intake of iron.
Whether hyperchromic or hypochromic, treatment is primarily focused on treating the underlying condition. Iron supplements and increasing dietary iron intake can help treat iron deficiency anemia, but iron supplements are not recommended for people who are not iron deficient ( excess iron can build up in the liver and heart). used in more serious cases.
Mean corpuscular volume (MCV)
Average corpuscular volume (MCV) measures the average volume of red blood cells, that is, the actual size of the cells themselves.
The normal range for VCM is 80 to 96 femtoliters per cell.
A low MCV indicates that the red blood cells are small or microcytic . Possible reasons include :
- Iron deficiency
- Lead poisoning
- Thalassemia ( thalassemia is a genetic disorder characterized by abnormal hemoglobin)
A high MCV means that the red blood cells are larger than normal or macrocytic cells. The causes of macrocytic anemia include :
- Vitamin B12 deficiency
- Folic acid deficiency (both vitamin B12 and folic acid deficiencies are also called megaloblastic anemia due to macrocytic red blood cells)
- Liver disease
- Medicines such as chemotherapy drugs and retroviral drugs to treat HIV.
It is important to note that the person may have anemia and a normal MCV. This is called normocytic anemia. The reasons may include :
- Sudden blood loss
- Renal insufficiency
- Hemolytic anemia
- Lack of nutrients
- Chronic disease anemia
- Rheumatoid arthritis
- Giant cell arteritis
Mean corpuscular hemoglobin (MCH)
Average corpuscular hemoglobin (MCH) is the average amount of hemoglobin per red blood cell in a blood sample. The normal range for MCH is 27 to 32 picograms per cell.
The MCH value is directly related to the MCV value and some healthcare providers find this test redundant. Therefore, if the size of the red blood cells is large (measured by MCV), the amount of hemoglobin per red blood cell will be high (measured by MCH) and vice versa.
Although HCM can be used alone to detect hyper, hypo, or normocytic anemia, MCV should be considered in conjunction with HCM, since cell volume directly affects the hemoglobin content of the cell.
Red blood cell distribution width (RDW)
Red blood cell distribution width (RDW) is a test that reflects the variability in the size of red blood cells (and is proportional to the standard deviation of MCV). A normal RDW will mean that all the red blood cells are the same size, while a higher RDW means that there is more variability in the size of the red blood cells.
Some healthcare providers believe that RDW is one of the most helpful red blood cell indicators for making a diagnosis. In addition to its role in diagnosing anemia, an elevated RDW can predict the presence of coronary heart disease in people with high blood pressure.
A high RDW also indicates an early nutritional deficiency that cannot be detected by other tests alone. Finally, it is a good test to determine if more tests are needed, such as a peripheral blood smear.
The normal range for RDW is 11.5 to 14.5 percent.
RDW is most useful when evaluated in conjunction with MCV. Examples of some of the reasons include:
High RDW and low MCV (microcytic):
- iron deficiency anemia
- Sickle cell anemia
High RDW and normal MCV (normocytic):
- iron deficiency anemia
- Combined anemias
- Bleeding (after a few days)
- Hemoglobin variants
High RDW and high MCV (macrocytic):
- Vitamin B12 deficiency
- Folic acid deficiency
- Cold agglutinin disease
- Myelodysplastic syndrome
- Immune hemolytic anemia
Normal RDW and high MCV :
- Liver disease (chronic)
- Aplastic anemia
- Alcohol related
Normal RDW and low MCV :
- Chronic disease anemia
- Some types of thalassemia
- Some abnormal hemoglobins
It is important to note that these are just a few examples and there are many possibilities.
Get the word of drug information
A complete blood count is a standard blood test that includes the number of red blood cells in addition to the number of white blood cells and platelets. The red blood cell count can tell doctors how many red blood cells you have, but it says little about the cause of any abnormalities.
Red blood cell indices, based on the characteristics of red blood cells, are useful not only to discover the cause of anemia, but also to diagnose diseases, even if the number of red blood cells is normal.
The combination of these indices also provides important clues for reducing anemia. The examples above are just a few of the possible causes, and sometimes determining the exact cause of anemia can be very difficult.
These blood tests are best used in conjunction with a complete medical history, a complete physical exam, and any indicated imaging techniques. Information about these blood tests can help you ask your healthcare provider questions so that you fully understand the diagnosis they made or the additional tests they recommend.
Increasingly, people are being encouraged to be actively involved in health care and to learn to make informed decisions about their health. Taking the time to study your lab values will help you make the right decision.
Frequently asked questions
Red blood cell scores are four indicators of the size and quality of red blood cells. It can help diagnose certain medical conditions.
Anemia is caused by a lack of healthy red blood cells, which are necessary to supply oxygen to the body. A person with anemia may feel more tired or colder than usual, or look especially pale.
A high mean corpuscular volume (MCV) does not clearly indicate cancer. However, it can provide useful information in the presence of cancer. For example, it can predict how chemotherapy might affect a person with rectal cancer.