Microcytosis is a term that describes red blood cells that are smaller than normal. The presence of microcytic red blood cells may be reported in blood test results.

Microcytosis is assessed using the MCV or Mean Corpuscular Volume index, which reports the average size of red blood cells. A normal MCV result is between 80.0 and 100.0 fL, although this reference value may vary from lab to lab.

If microcytosis is identified, it is important for it to be interpreted alongside other indices measured in the blood count, such as mean corpuscular hemoglobin (MCH), hemoglobin, mean corpuscular hemoglobin concentration (MCHC) and RDW, which look at different characteristics of red blood cells.

Common causes

Microcytosis is mainly related to nutritional changes or occurs due to situations that influence the formation of hemoglobin. Thus, the main causes of microcytosis are:

1. Thalassemia

Thalassemia is a genetic disease characterized by changes in how hemoglobin is synthesized. This condition is associated with a mutation in one or more globin chains, resulting in abnormalities in how red blood cells function In addition to the altered MCV, it is likely that other indices are also altered, such as MCH, MCHC, RDW and hemoglobin.

Due to abnormalities in how hemoglobin is formed, the way that oxygen is transported is also altered, which can lead to symptoms like fatigue, irritability, paleness and changes in breathing.

2. Hereditary spherocytosis

Hereditary or congenital spherocytosis is a disease characterized by changes in the red blood cell membrane. Red blood cells are smaller and less resistant, with a higher rate of red blood cell destruction. This condition is associated with a reduced number of red blood cells and lower MCV levels.

As the name suggests, spherocytosis is hereditary and patients are born with this condition. However, the severity of the disease can vary from person to person, and it is important to start treatment soon after birth ad guided by a hematologist.

3. Infections

Chronic infections can also result in microcytic red blood cells. The persistence of the infectious agents can result in nutritional deficiencies and changes in the immune system, altering not only hematological indices but also other laboratory parameters.

To confirm an infection, it is important for the doctor to order other lab tests, like a C-reactive protein (CRP) test, urine tests and microbiological tests. A blood count may help to spot an infection, but other tests are necessary to confirm a diagnosis and begin appropriate treatment.

4. Iron deficiency anemia

Iron deficiency anemia is characterized by low levels of iron circulating in the blood. This can be caused by a diet poor in iron or as a consequence of bleeding or heavy periods.

A decrease in the amount of iron directly impacts hemoglobin levels, as iron is essential for the formation of hemoglobin. Therefore, in the absence of iron, there is a decrease in the amount of hemoglobin, which can lead to signs and symptoms, such as weakness, frequent fatigue, feeling faint, hair loss, weakened nails and lack of appetite.

This condition can often be managed by changing eating habits and increasing your iron intake through foods like spinach, beans and meat. Check-out other iron-rich foods you can include in your diet.

5. Anemia of chronic disease

Anemia of chronic disease is a type of anemia that commonly occurs in hospitalized patients, with changes not only in the MCV levels, but also in MCH, MCHC, RDW and hemoglobin levels. This type of anemia is more common in patients with chronic infections, inflammatory diseases and cancer.

Because this type of anemia usually occurs during treatment and monitoring of another disease, diagnosis and treatment should be initiated immediately to prevent further complications.

What does mild microcytosis mean?

Mild microcytosis is a term that may be present in a blood test report when it is found that only the MCV is altered and the value is close to normal. It is not usually taken into account when interpreting other test results, as it is usually temporary and not harmful.

However, when MCV values are very low, it is important to check if any other red blood cell value is altered. If the other indices are normal, the doctor will typically repeat the blood work.

Is microcytosis serious?

The severity of microcytosis depends on the condition that is causing this alteration in the blood cells and depending on the number of cells affected, It can be caused by a simpler situation, such as a diet change, or more serious condition, such as heavy bleeding, which should be treated immediately.