RBC Indices: What They Are and What They Tell About Your Health

RBC Indices: What Are They and What They Tell About Your Health

RBC indices (red blood cell indices) are used to check the size of red blood cells and the amount of hemoglobin in your blood. RBC indices are part of a complete blood count (CBC) which is used to check the health of your blood. Usually, red blood cell indices can help diagnose various types of anemia and help identify the cause of the low red blood cell count.

Red blood cells look like doughnuts without the hole in the center and carry oxygen throughout your body. Red blood cells are also necessary to remove carbon dioxide from your body. If there are abnormalities with your RBC indices, you might find that you get tired easily, are short of breath, get dizzy, and have pale skin.

Some common reasons why problems can show up in your RBC blood tests are a lack of iron in your diet, vitamin B12 deficiency, blood loss, or a gastrointestinal disorder. Usually, if your RBC indices indicate a problem, your doctor will run further tests to establish the exact cause. Very often, increasing iron levels in your blood or addressing the underlying cause helps to normalize your red blood cell count.

In this article, I will look at the 3 main components of RBC indices and look at the causes why they can be too low or abnormally high.

What Are RBC Indices? What Are They Used For?

RBC indices are composed of 3 main components:

  • Mean corpuscular volume (MCV) of your blood cells.
  • Mean corpuscular hemoglobin (MCH).
  • Mean corpuscular hemoglobin concentration (MCHC).

The publication Clinical Methods states that red cell indices are used to identify the causes of various types of anemias. Along with the red blood cell count, the red cell distribution width (RDW) is also taken into account.1

According to the International Journal of Laboratory Hematology, red blood cell morphology is the assessment of the shape, color, size, and arrangement of red blood cells. RBC morphology can help to discover if the anemia is caused by incorrect DNA synthesis that impairs RBC production.2

Abnormal RBC indices can happen for a number of reasons. For example, you may have anemia because your body doesn’t produce enough red blood cells. Or blood loss during heavy menstruation could cause a drop in your hemoglobin levels. In some cases, anomalies in your red blood cell indices are the result of red cells getting destroyed too quickly.

What Are Normal RBC Indices?

Normal red blood cell count as part of a CBC blood test can help to determine if you have enough hemoglobin. According to doctors from the National Health Service, normal RBC count should be between 4.7 and 6.1 cells/mcL (cells per microliter) for men and 4.2 to 5.4 cells mcL for women.3

However, in diagnosing various types of anemias, total CBC count is just part of the story. Doctors need to check the red blood cell indices, in other words, know the MCV, MCH, and MCHC levels of the red blood cells.

Red blood cell mean corpuscular volume (MCV) is measured in femtoliters (fL), MCH in picograms (pg) and MCHC in grams per deciliter (g/dL). The normal RBC indices are as follows:

Normal MCV levels. According to Dr. Jerry Balentine on MedicineNet, MCV levels should be between 80 and 100 fL.4

Normal MCH levels. The average corpuscular hemoglobin levels in adults are 29 ± 2 picograms (pg) per red blood cell.1

Normal MCHC levels. Dr. Brian Yang Merrit who specializes in hematopathology says that mean corpuscular hemoglobin concentration (MCHC) should be 33-36 g/dL in adults.5  

Abnormal RBC Indices and What They Mean

If you are concerned about abnormal RBC indices from a CBC blood test, here are some reasons for abnormal test results.

High MCV

What does it mean in a blood test if you have high MCV that is more than 100fL? Here are some of the reasons.

Vitamin deficiency

A common reason for blood test results showing higher than normal levels of MCV is a vitamin B9 (folate) or vitamin B12 deficiency. Both folate and vitamin B12 are essential for proper brain function and to strengthen your immune system, and one symptom of a B12 deficiency is constant headaches or migraines.

A study published in the journal Clinical Medicine & Research found that larger than normal red blood cells are often a result of a vitamin B12 or folate deficiency. It was found that low levels of vitamins B12 and B9 affect DNA synthesis and red blood cell production.6

Liver disease

High MCV levels could also be a sign of liver disease as impaired liver function causes the red blood cell MCV to become larger.

According to Dr. Laurence Knott on Patient.info, chronic liver disease can deplete stores of vitamin B12. This will increase the mean corpuscular volume of red blood cells and lead to microcytosis (enlarged red blood cells) and a macrocytic class of anemia.7

Excessive alcohol consumption

Drinking too much alcohol is one of the habits that damage the liver and decreases its function. Researchers from the American Academy of Family Physicians say that elevated MCV levels are often seen in alcoholics. This is because large quantities of alcohol impact how the liver produces red blood cells.8

Hypothyroidism (underactive thyroid)

If you frequently feel fatigued, put on weight, have a puffy face, and MCV levels are above 100 fL, you may suffer from an underactive thyroid.

A study published in the Iranian Journal of Pediatric Hematology Oncology found that MCV was increased in individuals who suffered from thyroid problems. The researchers discovered that thyroid function impacts red blood cell production and can affect RBC indices.9


Another reason why CBC blood tests reveal elevated mean corpuscular volume of red blood cells include certain medications. The journal Clinical Medicine & Research reported that the side effect of some medications can cause increased MCV with or without anemia.6


You will also show signs of anemia if the average corpuscular volume of red cells is too low and below 80 fL. What are some of the reasons for low MCV?

Iron deficiency

If CBC test results show that MCV levels are below 80 fL (microcytosis), it could be an indication that you have iron deficiency anemia.

Iron deficiencies can happen for a number of reasons. For example, you may not be eating enough iron-rich foods or your body may not be absorbing enough iron. According to an expert in hematology and oncology, Dr. James Harper, blood test results that show low MCV and elevated blood platelet count usually signify iron deficiency anemia.10

Some of the other symptoms of iron deficiency anemia are constant fatigue, difficulty concentrating, difficulty shaking off illnesses, and cracks at the corner of the mouth.

Chronic bleeding

Heavy menstrual bleeding or gastrointestinal disorders can cause chronic blood loss which will lower your MCV levels.

According to the journal American Family Physician, a red blood cell count that shows MCV lower than 80 fL is often caused by blood loss. Abnormal red blood cells develop because the body can’t replenish the volume of red blood cells fast enough if there is chronic bleeding.11

Other reasons for low MCV

The Royal College of Pathologists of Australia report on other reasons why your MCV levels could be low. Some of these reasons include thalassemia – an inherited blood disorder, toxic lead poisoning, rare enzyme deficiencies, or sideroblastic anemia.12

If you have heavy menstrual periods, you should consult with your doctor.

High MCH

Let’s look at some of the reasons for abnormal MCH levels that are higher than the normal range, and why you could have more hemoglobin than normal in a single red blood cell.

Liver dysfunction

CBC blood test results that show higher than normal MCH and high MCV could be due to liver disease. The proper liver function is essential for the body to produce hemoglobin in the right amounts.

The journal Management of Anemia reports that liver disease is associated with different types of anemia. High MCH levels are often associated with macrocytic anemia when the liver isn’t functioning correctly.13

Another reason why you could have problems with your liver that result in high MCH levels is chronic alcohol abuse. Drinking alcohol for many years takes its toll on your liver and affects MCH levels. According to Professor of Hematology Dr. Vincent Herrin, abstaining from alcohol can help to reduce MCH levels in your blood.21

Vitamin B12 deficiency

A vitamin B12 deficiency can also result in the average concentration of hemoglobin in your red blood cells being higher than normal.

According to the publication Clinical Methods, low levels of vitamin B12 and folate contribute to elevated MCH. You might find that along with the symptoms of anemia, you also have difficulty sleeping and experience mood swings.1


It is generally more common that CBC test results show lower than normal MCH rather than elevated levels. Here are some of the reasons why you could have low mean corpuscular hemoglobin.

Iron deficiency anemia

Iron deficiency anemia is a condition in which your body can’t produce enough hemoglobin and it will show up as low MCH in test results.

According to a specialist in hematology, Dr. Stanley Schrier, doctors will check MCH and MCHC levels to see if they are low when checking for anemia. Because hemoglobin carries oxygen around the body, iron deficiency anemia and low hemoglobin leave a person feeling weak, suffering from headaches, and irritability.14

Thyroid dysfunction

One condition your doctor may check for if you have low MCH and signs of anemia is how your thyroid is functioning. Thyroid dysfunction can be a reason for having either low or high mean corpuscular hemoglobin.

For example, the Iranian Journal of Pediatric Hematology Oncology reported that patients who have an overactive or underactive thyroid show signs of thyroid dysfunction. Sometimes MCH levels were elevated, sometimes they were lower than normal.9

Gastric surgery

Because of malabsorption caused by gastric surgery your body may have trouble absorbing iron resulting in low MCH.

According to the journal BioMed Research International, some individuals who have had gastric surgery show symptoms of anemia. Researchers found that gastric bypass surgery makes people more prone to getting infections, suffer from chronic disease, or autoimmune conditions that can impact on the health of a person’s blood.15

Celiac disease

Celiac disease is another reason why your body doesn’t absorb enough iron and shows symptoms low MCH levels in a lab test.

CBC blood tests often show abnormalities in RBC indices in people with celiac. For example, the Indian Journal of Pediatrics reported that doctors often have to address the iron deficiency in celiac patients. Iron levels are boosted by using iron supplements and sticking to a gluten-free diet. In time, MCH levels increase in the blood.16

Abnormal MCHC levels

Knowing the average concentration of hemoglobin in your blood cells is also important for doctors to diagnose causes of anemia.

Rather than show the amount of hemoglobin per red blood cell (MCH), MCHC blood test show the amount of hemoglobin content in the cell volume. So, it is possible for people suffering from anemia to have increased MCH but normal MCHC levels. For example, the book Clinical Practices says that vitamin B12 deficiency results in larger than normal red blood cells, but the hemoglobin could remain normal.1

What can cause abnormal MCHC levels? Here are a few of the most common causes of low mean corpuscular hemoglobin concentration.

According to many studies into RBC indices, the reasons for low MCHC levels are often related to anemia caused by the following:

  • Low iron levels in the blood
  • Malabsorption due to gastrointestinal problems like Crohn’s disease, celiac, or Helicobacter pylori infection.
  • Folate (vitamin B9) deficiency
  • Excessive bleeding

For example, according to the journal The Medical Clinics of North America, low MCHC levels are usually caused by not having enough hemoglobin in the blood cells.17

What to Do When RBC Indices Are Abnormal

If CBC blood test results show that your red blood count indices are abnormal, your doctor will usually recommend increasing your iron and getting enough B-group vitamins.

Here are some natural ways to improve your RBC indices to treat anemia and also prevent low hemoglobin levels in your blood.

How to boost iron levels naturally

Increasing your dietary intake of iron can help to increase MCV, MCH, and MCHC levels in your blood.

According to doctors from the Mayo Clinic, consuming more iron-rich foods can reduce your risk of iron deficiency anemia. Red meat, poultry, and seafood are among some of the best sources of iron. If you are a vegetarian or vegan, you can increase your consumption of beans, dark green leafy vegetables, and vitamin C which helps iron absorption.18

Increase vitamin B and folic acid

Another way to improve your RBC indices if they are too low is to increase your intake of foods rich in B vitamins and folic acid.

Doctors from the National Health Service say that some of the best dietary sources of B vitamins are milk, eggs, meat, and fish. Also, dark green leafy vegetables contain good amounts of folic acid as well as iron.19

Iron supplements

If your RBC indices show that you are very anemic, doctors may suggest that you take iron supplements to reduce anemia and its symptoms.

According to the American Journal of Medicine, adults require about 20mg of iron every day. However, if you have celiac disease or have had gastric surgery, doctors may recommend that you take more iron supplements to prevent anemia.20

Avoid habits that increase RBC indices

If CBC blood tests show that your RBC indices are too high, you should avoid habits that can cause abnormalities in your red blood cells.

Here are some simple things you can do to help normalize your MCH, MCV, and MCHC levels:

  • Reduce alcohol consumption to help your liver recover.
  • Drink plenty of water to flush toxins from your kidneys and improve your blood work.
  • Address any thyroid issues that you have to help regulate your production of red blood cells.

Read my other related articles:

Medical References

  1. NCBI. Red cell indices.
  2. Int J Lab Hematol.2013 Jun;35(3):351-7.
  3. NHS. Red blood cell count.
  4. MedicineNet. Anemia.
  5. Medscape. MCH and MCHC.
  6. Clin Med Res. 2006 Sep; 4(3): 236–241.
  7. PatientInfo. Macrocytosis and macrocytic anemia.
  8. Am Fam Physician.2009 Feb 1;79(3):203-208.
  9. Iran J Ped Hematol Oncol. 2013; 3(2): 73–77.
  10. Medscape. Iron deficiency anemia.
  11. Am Fam Physician.2010 Nov 1;82(9):1117-1122.
  12. RCPA. Mean cell volume.
  13. Management of anemia. pp 129-142.
  14. UpToDate. Anemia caused by low iron in adults.
  15. BioMed Res Int. 2013 (2013), Article ID 205467, 8 pages.
  16. Indian J Pediatr.2003 Dec;70(12):955-8.
  17. Med Clin North Am.1992 May;76(3):549-66.
  18. Iron deficiency anemia.
  19. NHS. Vitamins and minerals
  20. Am J Med. 2008 Nov; 121(11): 943–948.
  21. Medscape. Macrocytosis.

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