Definition of Anisocytosis

Anisocytosis is a medical condition characterized by abnormal size variability of red blood cells in blood. The sizes of red blood cells are not similar to each other. These uneven sizes of red blood cells are diagnosed in different blood disorder such as anaemia, thalassemia etc. Anisocytosis is diagnosed by blood smear preparation in the diagnostic lab.


Image 1: Anisocytosis

Symptoms of Anisocytosis

The vital functions of Red Blood Cells are to transport oxygen and nutrients to different tissues of the body. These provide energy to every tissue to work accordingly. In general, the sizes of the RBCs are equal and they efficiently hold and carry oxygen and nutrients. In anisocytosis, the RBCs are not of equal size and due to this reason the efficiency of holding and carrying of oxygen and nutrients are diminished. This affects whole physiological system. Individual with anisocytosis often feel the following symptoms:

  • Exhausted with less effortful job
  • Mild physical activity also cause tiredness
  • Dyspnoea or shortness of breathing is perceived difficulty of breathing
  • Hypoxia – it is a condition in which an area of the body or tissue is deprived of sufficient supply of oxygen.
  • Tachycardia- increased heart rate.

Anisocytosis condition is quite common with anaemia and following symptoms are common in this condition

  • Paleness in skin, nails and eyeball
  • Body temperature is less than usual
  • Coldness in palm and feet
  • Headache
  • vertigo

Causes of Anisocytosis

Erythropoiesis (development of RBCs) originates in red bone marrow. Kidney secretes erythropoietin hormone which stimulates red bone marrow for production of RBCs and maturation factors such as vitamin B12, folic acid and iron help to mature the RBCs. In anisocytosis, the RBCs are under developed and the following reasons are may promote the condition:

Deficiency of Folic acid

Folic acid is essential for synthesis of DNA which has vital role in cell maturation and cell division. Deficiency of folic acid leads to abnormal and diminished DNA and consequently failure of nuclear maturation and RBCs differ in size.

Deficiency of Vitamin B12

The function of vitamin B12 is similar to folic acid. Vitamin B12 which is secreted from gastric glands helps to absorb the nutrients with the help of intrinsic factors. Deficiency of vitamin B12 leads to immature RBCs and poor absorption of essential nutrients e.g. folic acid and iron.

Pernicious anaemia

In this condition the basic abnormality is in gastric mucosa that fails to produce normal gastric secretions and thus fails to produce intrinsic factors. In absence of intrinsic factors, vitamin B12 is unable to work properly.

Liver disease

After absorption of Vitamin B12 from the GI tract, it is first stored in liver and then slowly released as needed by the bone marrow. In case of liver disease, storage and discharge of vitamin B12 is hampered.

Kidney disease

In case of degenerative condition, kidney is unable to secrete erythropoietin hormone which inhibit the Red Blood Cells production.


Anaemia is of different types but in all cases the amount of RBCs and haemoglobin is less. The condition may arise due to lack of iron, vitamin B12 and Folic acids.


It is a congenital genetic disorder where the bonding of protein subunits, denoted as α subunit and β subunit is hampered in haemoglobin. Thalassemia leads to severe anaemia and life threatening condition.

Blood Transfusion

The people go for blood transfusion that often has anisocytosis because of the mismatch of the size of RBCs of donor blood to that of recipient blood. The size of the RBCs is an important factor which should be taken care before transfusion of blood.


For detection of anisocytosis it is essential to perform the blood smear test.

Blood Smear Test

In this test, the thin film of blood is prepared by gradual and smooth spreading of blood on a slide in addition with applicable dye. Wait for some times till the thin film smear become dry and that slide is examined under electronic microscope to determine the size of each Red Blood Cell. This test helps to identify the abnormality of size of the RBCs.

After confirmation of anisocytosis, the reason of this disorder identification is required and for that some routine diagnosis can be followed. These are:

  • T3, T4 and TSH level checking for thyroid gland functioning
  • Haemoglobin estimation for detection of anaemia
  • Adrenal gland functioning
  • Calcium test

Treatment of Anisocytosis

Identification of underlying cause is the vital part for anisocytosis as it is associated with different disease conditions. Anisocytosis do not having any proper treatment but the treatment of underlying cause can reversible the anisocytosis condition. As early as the reason is determined the treatment will be effective as the enlisted diseases are more fatal than the anisocytosis and advanced stages of underlying disease treatments are quite difficult and costly.

Supplementation of Vitamin B12 and Folic acids helps to reduce the symptoms if anisocytosis occur due to deficiency of Vitamin B12 or Folic acids.



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