8 Types of Anemia | Based on Morphology & Causes

“Anaemia is an+aemia (no+blood). It is a condition wherein there is decreased oxygen-carrying capacity by the blood.”

Red blood cells carry oxygen to different parts of the body.

They have an iron pigment, namely hemoglobin, to do that.

Anemia can occur either due to a

  • Decreased RBC count
  • Decreased hemoglobin, or
  • Decreased blood volume.

Any of these factors can lead to insufficient oxygen-carrying capacity by the blood to the tissues and cells by the blood.

Red blood cells (RBCs) per deciliter of blood are kept constant to aid proper respiration.

When the RBC count per mm of blood falls, we experience anemia.

This anemia is mostly found in women and children. The rate of incidence is as below.

  1. Pregnant women (38%)
  2. Children below two years of age (14%)
  3. Elderly people above 65 years (10%)
  4. Women aged between 12 to 49 years (9%)

But of them, anemia is mostly seen in women with abnormal menstruation, during pregnancy, and in children with poor nutrition.

Clinically anemia is of following types like

  1. Normocytic anemia
  2. megaloblastic anemia
  3. microcytic anemia

When blood is examined under a microscope, there are three types of anemia like

Normocytic anemia

  • As the name indicates, the pateint has Red blood cells with normal size and sufficient hemoglobin.
  • But, the problem is there is a decrease in erythrocyte count rather than the changes in RBC.
  • This is caused due to blood loss in injury, menstruation, etc. in many cases.
  • However, it can also be caused due to deficiency of erythropoietin where there is less synthesis of red blood cells in the bone marrow.

Megaloblastic anemia

  • In this type, the red blood cells are enormous.
  • This occurs as the cells are released into blood before they get fully matured.
  • They are formed with incomplete cell division in the bone marrow leading to a larger size than the normal size.
  • They can have sufficient hemoglobin or less.

Microcytic anemia

  • In this type, the RBC cells are smaller in size than the normal ones.
  • This is mostly due to insufficient hemoglobin levels.
  • The oxygen-carrying capacity of the blood depends on the hemoglobin portion situated inside red blood cells (RBCs).
  • So, if there is anemia we experience weakness and lack of strength.
  • These RBCs are formed in the red bone marrow of the large bones in the body.
  • They have a life span of 120 days. They become fragile due to wear and tear during circulation and get destroyed in the liver and spleen.
  • The dead ones are replaced by the new RBCs.
  • The cells formed in the bone marrow are quite large than normal RBC’s and hence vitamins like folic acid and Vit-B12 help in their multiplication to RBCs.

Types of Anemia Scientifically

1. Aplastic anemia

  • This is a condition with damage to the red bone marrow of long bones.
  • As we know, the red bone marrow is the site of the formation of blood cells (erythropoiesis).
  • But due to the effect of radiation or drugs this bone marrow gets damaged.
  • Hence, there is an inability to produce enough RBCs required for sufficient oxygenation.

2. Megaloblastic Anemia

  • As the name indicates, the cells formed are very large.
Types of Anemia
Image showing large-sized RBC cells among normal RBC cells.
  • This is due to the lack of vitamin-12 or folic acid leading to mega RBCs.
  • This again happens due to improper multiplication of large cells formed in the bone marrow.
  • Hence RBC count is low due to improper cell multiplication and production.
  • Further due to their large size they easily get destroyed and hence their life span is small, unlike normal RBCs 120 days.
  • Thus overall RBC count falls due to lack of the above vitamins.
  • This is otherwise called pernicious anemia if the Vitamin-B12 is deficient.
  • So it is advised to take vitamin supplements after consulting a physician.

3. Genetic or hereditary anemia

  • This condition is less common, but the patient suffers the issue for entire life.
  • This condition can be termed as hemolytic anemia (haemo-related to RBC and Lytic- means breakage).
  • RBC cells flowing in the blood are broken down before the normal life span of 120 days.
  • This destruction in a short time leads to decreased RBC count.
  • The damage is due to their weak or fragile and abnormal structure instead of normal biconcave. Examples include
Types of anemia-sickle anemia

4. Sickle cell anemia

  • As the name indicates the RBCs formed are sickle-shaped instead of biconcave.
  • Due to abnormal shape, they are easily susceptible to endoplasmic reticulum destruction in the liver and spleen.
  • Thus their life span is small and less than the usual RBCs of 120 days.
  • They get destroyed and have a short life span, so the RBC count remains low leading to anemia.

5. Spherocytosis anemia

Here the cells are spherical shaped instead of biconcave, and they get destroyed faster.

Similar to sickle cell anemia, they have short life spans.

6. Decreased Hemoglobin content

  • Here the RBC cells are devoid of sufficient hemoglobin.
  • This can be due to dietary protein insufficiency or else decreased iron content.

Ex: Hypochromic or microcytic anaemia+ hypo+chromic=less colored and mircocytic= small cell size.

  • As we see, this is anemia due to low iron levels in the body.
  • There are moderate amounts of hemoglobin due to iron deficiency such that cells are small and blood looks pale.

7. Hemorrhagic Anemia

  • This happens when there is a blood loss due to an accident, during delivery etc.
  • Here total blood volume including RBC numbers is low.
  • This is seen in women in most cases as they lose blood even due to the menstrual cycle.
  • This blood loss anemia can be rectified by transfusion.

8. Anemia due to less RBC count

  • This is a type of anemia where there is no sufficient number of red blood cells.
  • This is due to a lack of production of RBC or excess destruction of RBC.
  • This type of anemia includes aplastic anemia megaloblastic, pernicious anemia. 
  • Further types include genetic-related anemic conditions like sickle anemia, hereditary spherocytosis, erythroblastosis fetalis, etc.
  • For immediate rescue, RBC cells are transfused to the patient.
  • But in the long run, the effort is to enhance new RBC formation.

The causes of anemia are

a) Iron deficiency

b) Vitamin B12 Deficiency

c) Vitamin B9 (folate) deficiency

d) A decrease in blood cell formation

e) Blood loss due to hemorrhage

f) Excessive and premature destruction of red blood cells.

  • So anemia can occur when there is less volume of blood (in cases like severe bleeding).
  • Due to malnutrition, a decrease in RBC count can occur due to a decreased supply of Vitamins B12 and B9.
  • Decreased hemoglobin content can occur due to a lack of iron supplements in food.

Symptoms of anemia include:

Most symptoms go unnoticed, but sometimes there can be

1. Fatigue: Exhaustion due to physical exertion as blood cannot supply needed oxygen for chemical energy production.

2. Headache: This could be due to an insufficient supply of oxygen to the brain.

2. Paleness of mucous membranes like that below the eyelids etc.

3. In extreme conditions during exercise, the heart rises the cardiac output (volume of blood pumped) to meet the excess oxygen demands of the body.

In doing so, there can be chances of cardiac failure and death.

One can avoid anemia by proper diet, leafy vegetable consumption, and also iron supplements.

If one has a vitamin deficiency, it has to be corrected immediately.

Sometimes though vitamin-B12 is consumed by external supplements, the gut still may not absorb it.

So it is advised to consult a physician if the symptoms are troublesome.

2 thoughts on “8 Types of Anemia | Based on Morphology & Causes”

  1. It is very helpful. May you write a few summaries of the deficiency of red blood cells and email me, please.

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