Dear teachers (and students) of pathology,
I am having some trouble distinguishing between etiology and pathogenesis.
E.g. during atherosclerosis:
– Etiology = e.g. cholesterol, hypertension, smoking, obesity, diabetes etc.
– Pathogenesis = intimal inflammation (possibly caused by the deposition of cholesterol).
Is it “simply” a question of cause and effect/process?
Added by: Sara
On: May 8th 2012
Dear Sara,
Etiology states the cause of the disease, whereas pathogenesis states the disease mechanisms.
For atherosclerosis the distinction is perhaps a little difficult, since we have not demonstrated a single (or few) causes leading the the changes, but rather a combination of several issues. Another example might better illustrate the difference: For a simple acute cystitis (Danish: blærebetændelse), the etiology is most often bacterial infection with E. coli, whereas the pathogenesis includes the effects on the epithelial lining of the bacteria and the initiation and progression of an acute inflammatory response. It is the latter inflammation that causes the symptoms and the signs.
I’m sorry but what about hemophilia type A? What is the difference between its pathogenesis and etiology? I’m getting confused because it is an inherited disease. So, the etiology is gene disorder, right?
I’m no expert but i think you’re correct that the genetic defect is the etiology. I believe the pathogenesis, of mechanism, would be the resultant disorder of the tenase enzyme complex. “Three key enzyme complexes form on membrane surfaces of certain types of cells . Factor VIII is a component of the tenase complex in which it acts as a cofactor. Inadequate function of the tenase complex leads to reduced generation of thrombin. The consequence is formation of a defective coagulum, along with inadequate inhibition of fibrinolysis. These mechanisms result in bleeding diathesis observed in the clinical picture”.
http://nts.prolekare.cz/cls/odkazy/clc0511-727.pdf
Etiology is the REASON of a disease, pathogenesis is how signs, symptoms DEVELOPS. As an example of the difference, an abscess can be caused by (=the etiology) Staphylococci or E. coli or other microorganisms or can even be sterile such as in a cancer tumour, but the abscess develops in all cases the same way: as accumulation of neutrophilic granulocytes that produces large amount of toxic, tissue degrading enzymes. For hemophilia type A, the etiology is a mutation in the gene for clotting factor VIII, whereas the pathogenesis is related to the lack of function of the clotting factor, i.e. decreased clotting causing continuous bleeding. I admit that this example might be a little far-fetched.
Is it possible that one day when we understand the mechanism, or more precisely the reason, of gene changes, these will eventually become the pathogenesis instead of etiology as seen today?
I am not sure what you are asking. I would turn it around postulating that pathogenesis (i.e. how diseases are developed) in some circumstances will turn out to be the reason for a disease. For example, erroneous macrophage interaction making granulomas. This will turn pathogenesis into etiology.