How do doctors think? The answer to that question would fill quite a few blog posts, but we'll take one particular facet and examine it. When you come into the doctor's office with a fever, a cough, a headache, stomach pain, vomiting, or any other complaint, how does the doctor go about deciding what the cause of your illness is? Without knowing the cause, a correct decision regarding treatment is hard to come by, thus the underlying cause or etiology must be elucidated, or at least deciding in a general direction. One common way medical students are taught to think is by using the mnemonic in the title of this post. It is helpful for beginning students when looking at the presenting symptoms of a patient to be able to organize the differential diagnosis by etiology. As students grow more accustomed to seeing different constellations of symptoms and making diagnoses, the mnemonic becomes more cumbersome than helpful, but the basic process of elimination and prioritizing remains the same. The mnemonic stands for the following basic causes of disease:
V: Vascular, or to do with blood vessels. Are they leaky? Are they too constricted or dilated?
I: Infectious, or colonization with microorganisms. Bacteria, virus, fungus, parasite?
N: Neoplastic, or cancerous. Malignant or benign? Primary tumor or metastasis?
D: Drug reaction or side effect. Have new drugs been started recently? Are there illicit drugs involved?
I: Inflammatory. The body's reaction to insult...some inflammation is a good thing...too much leads to disease. Allergies? Psoriasis?
C: Congenital, or from birth. Is this a genetic problem? Inherited? In-utero physical malformation?
A: Autoimmune, or self-attack. Is the body's immune system recognizing self antigens as foreign and mounting an attack? As in rheumatoid arthritis or diabetes type 1?
T: Trauma--obvious. But ask anyways. The man with back pain just may have a knife buried between his shoulder blades and not know it. (This story is often bandied about...urban legend designed to make sure medical students ask the question? Maybe.)
E: Endocrine--having to do with hormones. Thyroid, pituitary, adrenal? Pancreas?
S: (Psycho) Social: psychiatric problems often have physical manifestations.
Almost any illness you can think of can be categorized into one of these areas. This is just the first step, but if this mnemonic is applied in an organized fashion, your doctor can arrive at the diagnosis and treatment with speed and accuracy.
Beginning tomorrow, the first week of my spring break will be spent at a doctor's office in SW Virginia putting this into practice. Practice makes perfect!