Anemia and its type

• A condition in which the number of red blood cells, the normal concentration of hemoglobin, or the hematocrit is below normal is called anemia.
• It decreases the blood’s oxygen carrying capacity.
• Anemia is usually a symptom of underlying diseases.
• There is usually an abnormally high amount of bilirubin in the plasma when anemia is due to the excessive destruction of erythrocytes.
• It results in producing characteristics jaundice of the skin and darkening of the feces.
• The various types of anemia are:

1. Hemorrhagic anemia

• Results from heavy blood loss.
• Can be acute and chronic type.
• Might be seen in some cases like heavy blood loss in menstrual bleeding.
• Also in severe wounds, or the sort of internal bleeding that accompanies a serious stomach ulcer.

In acute type

• Hemodilution occurs due to less number of RBC’s.
• After loss of blood, plasma of blood replaces within 24 hour.
• But, RBC’s takes at least 4-6 weeks.
• RBC’s are normocytic and normochromic morphologically.
• Decrease RBC’s results to hypoxia.
• Thus, hypoxia causes production of more number of RBC’s by stimulating bone marrow.
• Correction in the count of RBC’s occurs within 4-6 weeks.

In chronic type

• Results due to long time loss of blood either externally or internally.
• Lot of iron is lost resulting to iron deficiency.
• Hemoglobin synthesis thus affected decreasing its amount in cells.
• This results to decrease in cell size.
• RBC’s are microcytic and hypochromic morphologically.

2. Iron-deficiency anemia

• It is the most common type of anemia.
• It may be caused by long-term blood loss, low intake of iron, or faulty iron absorption.
• A hypochromic (low concentration of iron in erythrocytes) microcytic (small erythrocytes) anemia develops if there is deficiency of iron to make erythrocytes.

3. Aplastic anemia

• Characterized by failure of bone marrow to function normally.
• Generally caused by poisons such as lead, benzene or arsenic that hampers the production of RBC’s.
• It might be caused by radiation such as x-rays or atomic radiation that damages the bone marrow.
• Improper functioning of bone marrow results in drastic decrease in total count of erythrocytes and leukocytes.
• Viral infections, bacterial toxins, tuberculosis also cause this anemia.
• Morphologically, RBC’s are normocytic and normochromic.

4. Hemolytic anemia

• It occurs in case of infecting organisms such as the malarial parasites.
• As it enters the blood cells it reproduces until the cells actually burst.
• Such a rupture is called hemolysis (blood destruction), which causes the anemia.
• It might be hereditary or due to sickle cell anemia or an adverse reaction to a drug.
• Thalassemia is the name of group of hereditary hemolytic anemias.
• Impaired hemoglobin production is noticed which results in impaired erythrocyte production.
• It is most common in people of Mediterranean descent.
• Sickle cell anemia is another hereditary hemolytic anemic condition.
• Classified into two types.

Extrinsic hemolytic

• External factors destroy RBCs in this type.
• Antibodies, chemicals and drugs outside the blood cells hemolize healthy RBCs.
• Also called autoimmune hemolytic anemia.

Causes of external hemolytic anemia

• renal disorder
• hyper-splenism
• burns
• hepatitis, malaria and septicemia like infections
• various drugs like penicillin, sulfa drugs
• chemical substances poisoning like lead, coal and tar
• iso-aglutinins like anti-Rh
• autoimmune diseases like ulcerative colitis.
• liver failure, etc.

Intrinsic hemolytic anemia

• defective RBCs cause destruction of other normal RBCs.
• production of unhealthy RBCs with short life occurs in this type.
• destruction of these unhealthy RBCs takes place soon.
• often inherited type of anemia which includes sickle cell anemia and thalassemia.
• in this type, RBCs become more fragile(weak) and susceptible for hemolysis.

Sickle cell anemia

• It generally occurs in Blacks i.e., It affects 1 in 600 American blacks.
• It is a genetic hemolytic anemia.
• It results from the inheritance of the hemoglobin S-producing gene, which results in substitution of the amino-acid valine for glutamic acid in two of the four chains that compose the hemoglobin molecule.
• The abnormal red blood cells become rigid, rough and crescent shaped like a sickle so named sickle cell anemia.
• Sickle cells do not carry or release oxygen as well as normal erythrocytes do.
• Blood becomes more viscous by clogging of capillaries and other small blood vessels.
• It reduces the blood supply to some tissues thus producing swelling, pain and tissue destruction.
• Effective treatment has not been discovered yet.
• It might result to chronic fatigue and pain, increased susceptibility to infection, decreased bone marrow activity, and even death.

Image source: themedicalbio

Thalassemia

• Inherited disorder with abnormal hemoglobin.
• Also called Cooley’s anemia or mediterranean anemia.
• Common in countries like Thailand and some Mediterranean countries.
• Two types: α and β thalassemia.
• More common type is β thalassemia.
• Number of α  and β polypeptide chains is equal in case of normal hemoglobin.
• But, these number get imbalanced in this anemia condition.
• This is due to synthesis of globin genes in defective way.
• Thus, results in precipitation of polypeptide chains in the immature RBCS.
• In turn, erythropoiesis gets disturbed.
• Also, precipitation occurs in mature red cells resulting in hemolysis.

α- thalassemia

• Common in fetal life or in infancy.
• Less, absence or abnormal α- chains present.
• β chains are more in adults and γ chains are more in children.
• Thus, defective erythropoiesis results and finally hemolysis.
• Death of infants may occur immediately after birth or the case of stillborn noticed.

β-thalassemia

• β- chains less absent or abnormal and excess of alpha chains present.
• α chains precipitate leading to defective erythropoiesis.
• Thus, finally hemolysis occurs.

Image source: medlineplus

5. Pernicious anemia

• Also called Addison’s anemia.
• Caused by improper absorption of dietary vitamin B12.
• It is required for the complete maturation of the red blood cells.
• Antibodies are associated in major cases which destroy intrinsic factor in the stomach mucosa.
• Intrinsic factor is a protein that combines with vitamin B12.
• Thus, facilitates its absorption by the small intestine.
• In absence of intrinsic factor, immature red blood cells accumulate in the bone marrow.
• The mature blood cells count may drop as low as below 20% of normal, and immature cells enter the circulation.
• If diagnosed on time, it can be treated successfully with intramuscular injections of vitaminB12 and an improved diet.
• If left untreated, the disease may affect the nervous system causing decreased mobility, general weakness, and damage to the brain and spinal cord.
•  Common in old age and in females than in male.
• Disorders of thyroid may also cause this type of anemia.
• Lemon yellow colour of skin and red sore tongue are common features.
• Sensation of numbness, tingling, burning, etc. are some associated neurological disorders.
• Ataxia i.e., muscular incoordination observed in extreme conditions.

6. Megaloblastic anemia

• Folic acid deficiency causes this type of anemia.
• One of the essential maturation factor of RBCs.
• Deficiency condition does not allow RBCs to mature.
• Thus, characterized by defective DNA synthesis due to which nucleus remains immature.
• Megalobalstic and hypochromic RBCs are observed.
• Features similar to that of pernicious anemia.
• However, disorders related to neurons are not observed.

(Note: Nutrition deficiency anemia types are iron-deficiency anemia, pernicious anemia and megaloblastic anemia)

References:

i) https://my.clevelandclinic.org/health/diseases/3929-anemia

ii) https://www.webmd.com/a-to-z-guides/understanding-anemia-basics

Anemia and its type