What is Anisocytosis

‘Aniso’ means unequal and ‘cytosis’ means features, movement, and a number of cells. The term anisocytosis is used to describe a medical condition in which a person’s red blood cells are unequal in size which normally are almost equal in size.

‘Anisocytosis’  term lacks specificity because there are different ways in which cells can be unequal. Usually, anemia is the precursor of anisocytosis. It occurs due to a lack of iron in the blood. Anemia in turn is caused by various blood diseases. It can also be caused by drugs used to treat cancer. Therefore, anisocytosis acts as a symptom to diagnose anemia and further underlying cause.

Also, depending upon the underlying cause, cells can occur in different forms-

  • Macrocytosis (larger than normal)
  • Microcytosis (smaller than normal)
  • Mixed (some smaller and some larger than normal)

Anisocytosis itself isn’t harmful but depicts that there must be some disorder causing it.

In this article, we will talk about symptoms, causes, diagnosis, and treatment of anisocytosis.

Symptoms of anisocytosis

Since the shape and size of red blood cells is altered, their oxygen-carrying capacity is also affected and it is not transported as efficiently.

Symptoms that appear are-

– shortness of breath

– fatigue

– headache

– dizziness

– pale skin

– cold hands and feet

– chest pain

Anisocytosis itself is considered a symptom related to underlying blood disorders.

Causes of anisocytosis

Anisocytosis is generally caused by anemia. It is a disorder in which red blood cells are less in number, irregular in shape, and have iron deficiency. Hemoglobin amount may also be less. This affects the oxygen transportation by RBCs.

Anemia can occur in various forms. This includes-

  • Sickle cell anemia- In this type of anemia, red blood cells are abnormally crescent-shaped due to genetic make-up.
  • Iron deficiency anemia- This form occurs most commonly, due to iron deficiency in the body. There can be a lack of iron in nutrition or severe blood loss. It usually leads to RBCs smaller in size than normal.
  • Megaloblastic anemia- In this case, RBCs are fewer in number and larger in size than normal RBCs resulting in macrocytic anisocytosis. It occurs due to a lack of vitamin B-12 or folate in the diet.
  • Thalassemia- This type is also due to genetic constitution and results in the production of abnormal hemoglobin. It leads to microcytic anisocytosis.
  • Pernicious anemia- It is an autoimmune disorder that occurs when the body is unable to absorb vitamin B-12 properly. It causes macrocytic anisocytosis.
  • Autoimmune hemolytic anemias- It involves a set of disorders in which the immune system destroys the body’s own RBCs.
  • Aplastic anemia- It is related to bone marrow and affects the production of red blood cells. The body does not produce an adequate amount of red blood cells.

Drugs used to treat cancer, known as cytotoxic chemotherapy drugs can cause anisocytosis. It is also caused in people with cardiovascular diseases or cancer.

Sometimes, this condition also develops after blood transfusion but it is temporary.

There are other blood disorders as well that can lead to abnormal size of RBCs-

– myelodysplastic syndrome

– chronic liver disease

– Thyroid related disorders

– Protein deficiency

Such disorders are the underlying cause of anisocytosis, hence, it helps in detection of a more serious problem.

Diagnosing anisocytosis

Symptoms are experienced that can be used for diagnosis but to confirm the condition tests are required.

Anisocytosis is detected by a medical expert, scientist, hematologist or a pathologist in the laboratory by the use of blood smear.

Blood samples are collected and examined under a microscope to check if there is abnormality in shape or size.

Things to be considered while examining include-

  • number of red blood cells
  • cell volume
  • average amount and concentration of hemoglobin in each red blood cell
  • size of red cells

There are other various diagnostic tests that can be done-

– Serum iron levels

– Vitamin B-12 tests

– Folate test

– Ferritin test

– Complete blood count

If your report shows anisocytosis, the doctor may ask you to go through more tests to find out the underlying cause. Treatment should begin as soon as possible.

How anisocytosis is treated?

Since anisocytosis itself is a symptom of some underlying cause, the root problem has to be diagnosed and treated in order to get rid of it.

Anisocytosis occurring due to deficiency of iron or vitamin B-12 can be treated by covering up for deficiency through proper nutrition or supplements. Iron rich foods such as tofu, meat, eggs, fish, pulses and nuts can be consumed.

In disorders such as myelodysplastic syndrome, bone marrow might need to be replaced.

Anisocytosis related to anemia caused genetically might need a blood transfusion.

Anisocytosis in pregnancy

Anisocytosis during pregnancy is caused by a lack of iron. Pregnant women need more iron to produce RBCs for their growing baby.

Doctor might suggest you to go through other tests to check for iron deficiency or anemia, in case you have anisocytosis. Such disorders can be dangerous for the baby.

Fetus may be deprived of proper oxygen. You may be fatigued and experience other symptoms as well.

There is a risk of preterm labor. Complications can also occur.

Complications of anisocytosis

Several complications can be experienced if anisocytosis and its underlying cause are not treated on time and properly like-

– Destruction of the nervous system

– Increased heart rate

– Less number of white blood cells and platelets, hence, decreased efficiency of defence mechanism of body and increased clotting time

– In pregnant women, it can cause damage to the fetus. It does not receive oxygen properly. Development can be affected


Anisocytosis is the production of red blood cells, unequal in size and shape. It can be either macrocytosis or microcytosis depending upon the underlying cause.

This condition acts as a symptom to other underlying causes. Anemia is the most common cause. It can be of various types depending upon the reason.

Anisocytosis can be diagnosed with the help of symptoms and tests of different types, done by a skilled expert.

It should not be left untreated as it can pose severe complications on the body. Treatment can be done by getting rid of the root problem.

In pregnant women, anisocytosis occurs due to a lack of iron or vitamin B-13 and can cause issues to the fetus. This is why it should be treated as soon as possible.

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