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Anisocytosis describes red blood cells that are of different sizes. Normal red blood cells are generally the same size. Having red blood cells of unequal sizes may indicate anemia, a condition that can cause symptoms like fatigue and shortness of breath. Treatment depends on what’s causing anemia. “Aniso” means unequal, and cytosis refers to the movement, feathers, or number of cells.


Many of the symptoms result from decreased oxygen delivery to the body’s tissues and organs. Anisocytosis in turn is considered a symptom of many blood disorders.

This can lead to:


Shortness of breath



Cold hands and feet

Pale skin

Chest pain

Other conditions associated with Anisocytosis

Researchers have discovered that many conditions besides anemia are associated with anisocytosis as measured by a red cell distribution width (RDW ) test. A high RDW value has been associated with a higher overall death rate.

Doctors aren’t sure whether anisocytosis plays a role in the deterioration of health or if it is simply a marker of illness. Is it a cause or an effect? Could it be used more widely in the diagnosis of illness? Can it even predict outcomes? Scientists are interested in these questions. Other than anemia, some conditions that are associated with anisocytosis include

Cardiovascular disease:

                                            Many people with atrial fibrillation, coronary artery disease, and other heart problems have higher than normal RDW scores. To get information about mental health.

Liver disease:

                            One study suggested that RDW could be used to predict 3-month mortality in people with liver disease. Another study found that high RDW values were related to poor outcomes from hospitalization.

Kidney disease:

                               In one study of people with acute kidney failure, high RDW scores were identified in people who died within 28 days. A study of patients with kidney disease showed that RDW scores increased as people experienced more serious stages of the disease.

Colorectal cancer:

                                   Persons with colorectal cancer had lower overall survival rates when they had high RDW scores, showing anisocytosis. This was true whether the test was done before surgery or after.


Anisocytosis is identified by RDW and is classified according to the size of RBC measured by MCV (mean corpuscular volume). According to this, it can be divided into:

Anisocytosis with microcytosis-iron deficiency, sickle cell anemia

Anisocytosis with macrocytosis-folate or vitamin B12 deficiency, autoimmune hemolytic anemia, cytotoxic chemotherapy, chronic liver disease, myelodysplastic syndrome

Increased RDW is seen in iron deficiency anemia and decreased or normal in thalassemia major (cooley’s anemia), thalassemia intermedia

Anisocytosis with normal RBC size- early iron, vitamin B12 or folate deficiency, dimorphic anemia, sickle cell disease, chronic liver disease, myelodysplastic syndrome.


The treatment for anisocytosis depends on what is causing the condition. For example, anisocytosis is caused by anemia related to a diet low in vitamin B-12, folate, or iron will likely be treated by taking supplements and increasing the amount of these vitamins in your diet. 

People with other types of anemia, like sickle anemia or thalassemia, may require blood transfusion to treat their condition. People with myelodysplastic syndrome may need a bone marrow transplant.

Anisocytosis in pregnancy

Anisocytosis during pregnancy is most commonly caused by iron deficiency anemia. Pregnant women are at a higher risk of this because they need more iron to make RBCs for their growing baby. If you’re pregnant and have anisocytosis, your doctor will likely want to run other tests to see if you have anemia and begin treating it right away.

If left untreated, anisocytosis or its underlying cause leads to

Low levels of white blood cells and platelets

Nervous system damage

Rapid heart rate

Pregnancy complications, including serious birth defects in the spinal cord and brain of a developing fetus (neural tube defects)


There are some lifestyle changes that people can make to try and avoid anisocytosis. The main thing that a person can do is evaluate their diet to ensure they are consuming the right amount of vitamins and iron-rich foods. I am a medical student. I researched anisocytosis.

Writer name:           

                          Ifrah Khalid

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