31 August 2011

What is the difference between ‘Signs’ and ‘Symptoms?’

Posted by Jody under: Preventative Medicine .

You’ve probably heard the phrase ‘signs and symptoms of a disease’ and thought it was redundant. Actually, signs and symptoms are two different things.

Symptoms are what a patient might report to a doctor when complaining of illness. These things are subjective impressions. Taber’s Medical Dictionary defines “symptom” as “any perceptible change in the body or its functions that indicates disease of the kind or phases of disease”(1). Symptoms are analyzed by the onset (when they are first noticed), characteristics (such as severity, timing, location and things that make them seem worse or better), and course since onset (meaning, the progress of the symptoms through treatment). If you read a professional article on an illness, you may read the phrase, “The patient presents with ….” These are symptoms. What the patient describes may not be exactly what is happening to them biologically, but health care professionals have to use the patient’s description of their state in order to begin to determine their illness.

By contrast, a sign is “any objective evidence or manifestation of an illness or disordered function of the body. They are more or less definitive and obvious and apart from the patient’s impressions”(1). Signs are the actual biophysical characteristics of the illness, which health care professionals use to definitively diagnose the condition. Symptoms can point to more than one cause, but all the signs must be right in order for the diagnosis to be correct. For instance, a low red blood cell count is a sign of anemia. It’s a characteristic of the illness that is not apparent to the patient, so it could not be reported as a symptom. The corresponding symptom that the patient would complain of is constant fatigue. Likewise, if the red blood cell count is high, the diagnosis of anemia must be thrown out and other possibilities considered.

Some other useful medical terminology include:

Symptom Complex: synonymous with “Syndrome”

Syndrome: “A group of signs and symptoms of disordered function related to one another by means of some anatomical, physiological, or biochemical peculiarity…not including a cause for the illness but providing a framework of reference for investigating it”(1). Examples include Iliotibial Band Friction Syndrome; Irritable Bowel Syndrome; Toxic Shock Syndrome; Gulf War Syndrome. Some syndromes are diagnosed by the complex of symptoms and differential diagnosis, rather than by definitive test results (such as blood tests for particular microorganisms, etc.), as when the specific cause of the illness is not known. In other words, “syndrome” is often used to describe a cluster of symptoms for which there is no known cause, such as the much-disputed Gulf War Syndrome.

Differential Diagnosis: “the diagnosis of a disease by comparison of the symptoms of two or more similar diseases”(1). This is a common practice, but it occurs most often when the symptoms presented by the patient are vague and could be from more than one condition. Knowing all the possible diagnoses related to the symptoms will indicate to the physician or nurse practitioner which further questions to investigate to eliminate some of the possible diagnoses and narrow down the possibilities. Differential diagnoses will include all the illnesses that could fit what’s happening clinically with the patient. This list of other possible diseases must be gone through one at a time until all but one possible diagnosis is left.

People don’t guess when an urgent situation may occur. Thus, doctors, safety officials recommends you to have individual first aid kit in home, workplace, office, car.

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