In this lesson, you’re going to learn what etiology means and how etiology is broken down into three main categories. You’ll also go over a concrete example to demonstrate the etiology of a disease.
Background of Etiology
The last time your computer gave you the blue screen of death, did you figure out the cause? Okay, maybe you’re not a computer pro. How about this one? The last time you blew a tire on your car, did you figure out whether or not it was a nail, sharp rock, or something else that caused it?Just like when you search for the cause of a flat tire, doctors and scientists try to similarly figure out the cause of a person’s illness. If they know the cause, then they can treat the cause and do more for the patient then just treating their symptoms. Keep this in mind as we discuss the etiology of disease and go over some examples of this concept.
Definition of Etiology
When a doctor tries to figure out the cause of a disease, they are actually trying to figure out the etiology of the disease.
Etiology is the cause of a disease or the science that deals with such causes. The word etiology comes from the Greek etio-, which means ‘causation’ and -ology, which refers to the scientific study of something.You might be familiar with similar terms such as biology and geology. These words also refer to the scientific study of something. Biology is the study of life (bio) and geology is the study of the earth or rocks (geo).A disease’s etiology, or cause, generally falls into three main categories; intrinsic, extrinsic and idiopathic.
First we will talk about intrinsic etiologies. Intrinsic means coming from within. Therefore, any pathological, or disease-causing, change that has occurred from inside the body has occurred as a result of intrinsic factors.The following are examples of intrinsic factors:
- Inherited conditions, or conditions that are passed down to you from your parents. An example of this is hemophilia, a disorder that leads to excessive bleeding.
- Metabolic and endocrine, or hormone, disorders. These are abnormalities in the chemical signaling and interaction in the body. For example, Diabetes mellitus is an endocrine disease that causes high blood sugar.
- Neoplastic disorders or cancer where the cells of the body grow out of control.
- Problems with immunity, such as allergies, which are an overreaction of the immune system..
The second category of disease etiology is extrinsic etiologies. This means the cause of the disease, or pathological change, came from outside of the body.The following are examples of extrinsic factors:
- Infectious agents like bacteria, viruses, fungi, and parasites
- Animal bites or stings
- Chemicals, electricity, and radiation
- Iatrogenic causes: This is just a fancy way of saying that the problem resulted from a medical professional’s actions or within a medical setting.
The third and final category of disease etiology is idiopathic, or of unknown cause.
Remember, we are ‘idio’-ts for not knowing the disease etiology. Hopefully, that’ll help you remember the definition of this term.
Example of Disease Etiology
You’ve been given quite a few examples of disease etiology in the last section. Let’s go over one more very specific example so you can truly understand how broad a disease’s etiological nature may actually be.Let’s say that you are a doctor and one of your patients comes in complaining of gastroesophageal reflux disease. This is a disorder that is famous for causing heartburn as a result of gastric (stomach) acid coming back up into the esophagus.
Normally, a muscular area where the stomach and esophagus meet, called the lower esophageal sphincter (LES), acts like a valve and closes tightly unless there is food actively entering the stomach. In gastroesophageal reflux disease, the LES is weak or incompetent. This means it is unable to close properly, which allows stomach acid to leak back up into the esophagus.What is the etiology of gastroesophageal reflux disease? The main cause is a functional or mechanical problem with the LES which causes it to not close properly. The factors that lead to this problem can be either intrinsic or extrinsic.The following are intrinsic etiologies:
Pregnancy and obesity can lead to gastroesophageal reflux disease because both of these conditions increase physical pressure within the abdominal cavity. This causes an increase in the pressure within the stomach and thus the propensity for stomach acid to travel back up into the esophagus.
The following are extrinsic etiologies of gastroesophageal reflux disease:
- Tobacco and alcohol use
- Foods like chocolate and coffee
The biochemical factors within these foods may force the LES to relax, which will allow for stomach acid to flow back up into the esophagus. As you can see, there are many etiologies behind this one disease. Identifying a specific etiology allows health care providers to provide specific treatment.
Etiology, is the cause of a disease or the science that deals with such causes.The etiology of a disease is broken down into three main categories:
- Intrinsic, which means the cause is from inside the body, such as inherited conditions or an endocrine disorder like diabetes mellitus.
- Extrinsic, which means the cause is from outside the body, like an animal bite, chemical burn, radiation, and iatrogenic causes. Iatrogenic causes are those caused within a medical setting.
- Idiopathic, which means of a currently unknown cause.