Medical diagnosis

Medical diagnosis is the set of procedures and disciplined thought used by clinicians to determine the source, or etiology of a patient's distress. It is not always possible to diagnose precisely and quickly, and, in such situations, appropriate supportive care may be appropriate. It cannot be overemphasized that some abnormalities, including pain, cannot go untreated because they might contribute to the diagnosis. Better understanding of medical physiology shows that some forms of distress, especially pain, are disorders in themselves, and, untreated, will make the overall situation worse.

A few terms need to be available for this explanation. A symptom is a patient's direct ("I have a headache") or indirect (e.g., a child screaming) subjective description of an element of their distress. A sign is an objective observation (e.g., the presence or absence of a given reflex given the appropriate stimulus) or test result. Not all signs are actually significant; not all symptoms need explicit treatment.

Too frequently overlooked is the reality that a given patient may have, simultaneously, more than one disorder, or has comorbidities. The signs and symptoms may be a result of a combination of disorders. With greater knowledge of physiology, it can be seen that one disorder can exacerbate another, or that some combinations of signs and symptoms can be caused only by comorbid disorders.

Diagnostic approaches

Some parts of diagnosis, or at least of abnormalities on physical examination, have been observed for centuries and millenia, but the causative factors may not have been known. More modern medicine has gone through cycles and styles. At one time, it was appropriate to present a patient as a series of body system descriptions, with little overall assessment. A newer approach, problem-oriented medical diagnosis, centers around the signs and symptoms, and is incomplete until they are understood, or at least relieved.

With quite recent understanding of such things as molecular-level understanding of the body's reaction to stress, immune stimuli, and trauma, there is a more securely based, partial return to considering systems as affected by the body's internal signaling. For example, tumor necrosis factor (TNF) can be an important part of defense against cancer and infections, but, inappropriately generated, it can cause many autoimmune diseases. While the mechanisms are not completely understood, there is a linkage between certain forms of infection-related (i.e., septic) shock, and TNF produced a part of the response to the infection.