Medical diagnosis and its uses

A medical diagnosis is the process of determining which disease or condition explains a person's signs and symptoms.It is often referred to as a diagnosis, with the medical background implied.The information needed for a diagnosis is usually gleaned from the patient's medical history and physical examination.Often, one or more diagnostic procedures, such as medical tests, are also done during the procedure.Sometimes a postmortem diagnosis is considered a medical diagnosis.

Diagnosis is often challenging because many signs and symptoms are nonspecific.For example, redness of the skin (erythema) is itself a sign of many diseases, so it doesn't tell a healthcare professional what's wrong.Therefore, a differential diagnosis must be performed, in which several possible explanations are compared and contrasted.This involves the correlation of various information, followed by the recognition and differentiation of patterns.Sometimes this process is facilitated by having characteristic signs or symptoms (or a group of several).Diagnosis is a major part of the physician visit procedure.From a statistical point of view,diagnostic procedures involve classification tests.

Medical uses 

In terms of diagnostic procedures, a diagnosis can be viewed as an attempt to classify an individual's condition into separate and distinct categories in order to make medical decisions about treatment and prognosis.The diagnosis is then described, usually in terms of disease or other condition.(However, in the case of a misdiagnosis, the individual's actual disease or condition differs from the individual's diagnosis.)Diagnostic procedures can be performed by various healthcare professionals, such as physicians, physical therapists, dentists, podiatrists, optometrists, nurse practitioners, healthcare scientists, or physician assistants.Diagnostic procedures (and opinions derived therefrom) do not necessarily involve elucidating the aetiology of the disease or condition in question, that is, what causes the disease or condition.Such elucidation can be used to optimize treatment, further define prognosis, or prevent future recurrence of the disease or condition.

The initial mission is to detect medical indications to perform diagnostic procedures.Indications include:

Detect any deviations from known normal conditions, such as anatomy (the structure of the human body), physiology (how the body works), pathology (what can go wrong), psychology (the mind and behavior) and homeostasis (regarding the mechanisms that keep body systems in balance).Knowing what is normal and measuring a patient's current condition against those norms can help determine a patient's specific deviation from homeostasis and the degree of deviation, which in turn can help quantify indications for further diagnostic treatment.Complaints expressed by patients.The fact that a patient seeks a diagnosing physician is itself an indication to perform a diagnostic procedure.For example, during a doctor's visit, the doctor may already be performing a diagnostic procedure by observing the patient's gait from the waiting room to the doctor's office, even before she or he starts making any complaints.

Even during a diagnostic procedure that has already been performed, there may be an indication to perform another separate diagnostic procedure for another possibly concomitant disease or condition.This may occur due to the incidental discovery of a marker unrelated to the parameter of interest, as may occur in composite tests such as radiology studies such as magnetic resonance imaging or blood test panels which also include blood tests unrelated to that parameter ongoing diagnosis.