Hi there! =)
I’m thinking of discussing on Anemias today. Ok, here I just would like to do somekind of introduction towards Anemias. More or less, I will try to discuss on definition, basic pathogenesis, classifications, outcomes or perhaps some medical terms that we really need to know along the way.
Ok, guys, let us get into medical adventure of anemias lol (it’s not funny? Ok fine! -____-“)
(Kumar, et al: Robbins Basic Pathology. Red cell disorders 12:422, 2007)
1) Reduction in oxygen carrying capacity of blood
2) characterized by reduction in the total circulating red cell mass to below the normal range
Anemia can be due to
1) Excessive bleeding (heamorrhage). Such as trauma
2) Increased in RBC destruction. Such as heamolytic anemias
3) Decreased in RBC production. Such as Iron Defeciency anemia.
Those are the most common causes of anemias. It is important to know the reasons (factors) that lead to anemia cause it is the basis of classification of anemia. Remember, good classification leads to better diagnosis, good diagnosis will give a good treatment. Doctor who gives good treatment is simply a good doctor =)
Ok, let us take anemias as whole, cause there are countless types of anemias since some of anemias are due to genetic disorders.
There are few basic classifications of anemias based on different approaches
1) Classification of anemias based on pathogenesis
a) Heamolytic anemia ( increased destruction)
-Disorder in heamoglobin synthesis
Thalassemia (Deficient globin synthesis)
Sickled cell anemia (Unstable heamoglobin)
b) Impaired Production
-Disturbance in proliferation and maturation of erythroblast
-Defective heme synthesis
Iron deficiency anemia
-Defective globin synthesis
2) Classification based on morphology
There are few terminologies which need to be understood in the morphology of red cells in anemias
a) Cell size
-iron deficiency anemia
b) Degree of hemoglobinization
-Iron deficiency anemia
That is a handful of list isn’t it? Nevermind, we can take it one step at a time.
The immediate body response towards anemias are
-Organ failure (severe)
-Hypovolumic shock (severe)
Ok, we know that anemia has a marked decreased in oxygen carrying capacity.
The reduction in oxygen number blood somehow triggers the increase in erythropoeitin (hormone controlling the erythropoeisis) secretion by KIDNEY.
This will lead to these consequent events :-
1) Compensatory erythropoesis in the red bone marrow which leads to erythroid precursor hyperplasia
2) In further extent or chronic condition, erythropoesis can even happen outside the red marrow; this is called as extramedullary erythropoesis.
3) Because of the increased of RBC production, erythroblast couldn’t even have time to mature and they tend to exit the red marrow and enters the peripheral blood. The increased number of reticulocytes (immature RBC) in peripheral blood is called as RETICULOCYTOSIS.
4) Too many activity that should be done by the red marrow makes it to try to compensate its workload by expanding its volume. This leads to red marrow expansion which eventually defects the shape of a bone. But remember, it can only expand its volume towards some extent, if it has reached its limit, extramedullary erythropoesis will take part.
5) If the anemia is a hemolytic anemia, there is increased in the destruction of red cells. And destruction of red cells mostly happens outside the blood vessels (extravascular hemolysis). Now, it has already involved the reticuloendothelial system (consists of liver and spleen). Try to imagine, when there are extramedullary erythropoesis and extravascular hemolysis happened simultaneously at liver and spleen, doesn’t it increase the workload of both organs? These extensive activities will finally lead to Hepatosplenomegaly (enlargement of liver and spleen)
6) Also, when there is increased in hemolysis, it will lead to the accumulation of iron in the blood and tissue. Accumulation of iron in tissue (hemosiderosis) will eventually leads to the destruction of tissue (hemochromatosis). It will ultimately lead to endocrine failure (usually pancrease and liver) and heart failure.
Those are the generalised pathogenesis of anemias.
Ok, that was a long and mouthful explanation lol. Now I would like to list down terms that we really need to know :-
Mean Corpuscular Volume – average VOLUME of heamoglobin in a red cell
Mean Corpuscular Hemoglobin – average MASS of heamoglobin in a red cell
Mean Corpuscular Heamoglobin Concentration – average CONCENTRATION of hemoglobin in a given volume of red cells
Erythropoesis – process of formation of erythrocytes (RBC) in the red marrow of a bone (long bone in children while flat bone in adults)
Erythropoetin – hormone releases by peritubular capillary endothelial cells of the KIDNEY to regulate erythropoesis
Extramedullary erythropoesis – erythropoesis that happens outside the medulla of bone, usually at the reticuloendothelial system (liver and spleen)
Hemolysis – process of destruction of RBCs which usually happens at the liver and spleen and done by mononuclear phagocytic cells; Kupffer cells in the liver and splenic macrophage in the spleen.
Hepatosplenomegaly – enlargement of liver and spleen due to compensatory mechanism
Hemosiderosis – accumulation of iron in tissue without presenting any tissue damage
Hemochromatosis – accumulation of iron in tissue with marked tissue damage
Those are pretty much about the general ideas on anemias. We will discuss extensively on different types of anemia individually, so we would have a better sight about this common disease.
Hope this article will help you in any way, and not to forget, please read more, cause the only way for you to understand medicine is through reading. Thank you so much and goodluck! =)