Mean corpuscular volume: what does it mean?

The mean corpuscular volume is related to the size of the red blood cells. Read on and learn why this value is important and what happens when it is altered.

Last update: December 24, 2021

Mean corpuscular volume (MCV) is a value or parameter of blood related to the average volume of red blood cells. It is estimated through an exam that can be part of a more complete analysis or study.

This test is simple and does not require any particular preparation. Although sometimes it is required to do it on an empty stomach if other studies have to be carried out at the same time. The results can denote whether the mean corpuscular volume is high or low.

Know if it is altered is essential in the diagnosis of some blood disorders, such as anemia. However, this cannot be considered in isolation, but other values ​​must be observed by the physician as well.

What is mean corpuscular volume and what is it for?

In the blood there are three kinds of corpuscles:

  • Red blood cells: also called erythrocytes or red blood cells.
  • White blood cells: or leukocytes.
  • Platelets: known as thrombocytes.

Red blood cells are responsible for carrying oxygen from the lungs to the different tissues of the body and transporting carbon dioxide in the opposite direction. But if the red blood cells are too small or too large, it could be indicative of some disorder.

For this reason, studies are carried out, such as the mean corpuscular volume (MCV). In said test the average size of erythrocytes is estimated, whose normal diameter should be between 6 and 8 microns (µm). This is a measure of length equal to one millionth of a meter.

In this sense, the mean corpuscular volume allows confirming or ruling out the diagnosis of anemia or other health problems; as well as follow-up in the treatment of this pathology.

At the request of the doctor, the person can take this exam as part of a general check-up or if you have certain symptoms, such as paleness, bruising and unexplained fatigue, cold extremities, unusual bleeding.

Red blood cells must be shaped and sized appropriately to do their job. If these parameters are altered, there may be some specific type of anemia.


Preparation, procedure and risks

The blood test to measure mean corpuscular volume it does not require special preparation. You may be asked to fast several hours beforehand, as other tests are sometimes done together, such as blood triglycerides or cholesterol levels.

As for the procedure, it is as follows:

  1. A healthcare professional takes a blood sample from a vein, usually from the arm.
  2. The blood is put into a test tube. The amount will depend on the tests to be performed.

Some people may experience some nervousness at this time when the needle is inserted. You may also feel discomfort from the puncture. But the procedure is quick and low risk..

Once the sample is extracted, it is taken to the laboratory, where the mean corpuscular volume can be measured with different devices that analyze changes in an electric current or in a light emission.



What do the results mean?

The VCM is a volume, therefore, is expressed in units of capacity. But since the blood corpuscles are so small, the measurement is in fentoliters (fL), which is 10-fifteen liters.

The normal value of the mean corpuscular volume should be between 80 and 100 fL. A normal VAW may mean that there is indeed no disorder. However, even with such normality, it is possible that there are two populations of red blood cells: some large and others small.

On the other hand, altered levels in the mean corpuscular volume may indicate a health problem, but not always. And it is that VAW changes with age or is influenced by physical activity, diet, medications and menstruation.

According to research, averages vary a bit between different geographic areas, which is why laboratories must adjust the values ​​according to the population with which they work.

Low mean corpuscular volume

If the results show smaller red blood cells than expected, it could be a sign of different pathologies:

  • Iron deficiency anemia.
  • Thalassemia
  • Congenital spherocytosis.
  • Chronic infections

Medium high corpuscular volume

On the contrary, if the results show that the red cells are larger than normal, it may be indicative of the following:

  • Pernicious or megaloblastic anemia.
  • Lack of vitamin B12.
  • Low folic acid.
  • Liver disorders
  • Bone marrow problems
  • Hypothyroidism
  • Myelodysplastic syndromes.
Iron deficiency anemia is one of the most common and usually presents a low MCV.

What to do when there are alterations in the mean corpuscular volume?

The mean corpuscular volume test can be part of a complete blood count or blood count. However, the VCM alone does not allow a diagnosis.

In fact, to confirm that it is anemia or another pathology, the doctor must observe the total red blood cell count and the hemoglobin concentration values. They will also review the patient’s medical history.

Even, other tests may be ordered, such as mean corpuscular hemoglobin or HCM. Therefore, without a complete and accurate diagnosis, treatment should not proceed.

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