Internal medicine, also known as general medicine in Commonwealth nations, is a medical specialty for medical doctors focused on the prevention, diagnosis, and treatment of diseases in adults. Its namesake stems from "treatment of diseases of the internal organs".[1] Medical practitioners of internal medicine are referred to as internists, or physicians in Commonwealth nations.[2] Internists possess specialized skills in managing patients with undifferentiated or multi-system disease processes. They provide care to both hospitalized (inpatient) and ambulatory (outpatient) patients and often contribute significantly to teaching and research. Internists are qualified physicians who have undergone postgraduate training in internal medicine, and should not be confused with "interns",[3] a term commonly used for a medical doctor who has obtained a medical degree but does not yet have a license to practice medicine unsupervised.[4][5]
Internists primarily work in hospitals, as their patients are frequently seriously ill or require extensive medical tests. Internists often have subspecialty interests in diseases affecting particular organs or organ systems. The certification process and available subspecialties may vary across different countries.
The term internal medicine in English has its etymology in the 19th-century German term Innere Medizin. Originally,[7] internal medicine focused on determining the underlying "internal" or pathological causes of symptoms and syndromes through a combination of medical tests and bedside clinical examination of patients. It emphasized treatment of the diseases affecting the internal organs of the body.[1] This approach differed from earlier generations of physicians, such as the 17th-century English physician Thomas Sydenham, known as the father of English medicine or "the English Hippocrates." Sydenham developed the field of nosology (the study of diseases) through a clinical approach that involved diagnosing and managing diseases based on careful bedside observation of the natural history of disease and their treatment.[8] Sydenham emphasized understanding the internal mechanisms and causes of symptoms rather than dissecting cadavers and scrutinizing the internal workings of the body.[9]
In the 17th century, there was a shift towards anatomical pathology and laboratory studies, and Giovanni Battista Morgagni, an Italian anatomist of the 18th century, is considered the father of anatomical pathology.[10] Laboratory investigations gained increasing significance, with contributions from physicians like German physician and bacteriologist Robert Koch in the 19th century.[6] During this time, internal medicine emerged as a field that integrated the clinical approach with the use of investigations.[11] Many American physicians of the early 20th century studied medicine in Germany and introduced this medical field to the United States, adopting the name "internal medicine" in imitation of the existing German term.[7]
Internal medicine specialists, also referred to as general internal medicine specialists or general medicine physicians in Commonwealth countries,[14] are specialized physicians trained to manage complex or multisystem disease conditions that single-organ specialists may not be equipped to handle.[15] They are often called upon to address undifferentiated presentations that do not fit neatly within the scope of a single-organ specialty,[16] such as shortness of breath, fatigue, weight loss, chest pain, confusion, or alterations in conscious state.[14] They may manage serious acute illnesses that affect multiple organ systems concurrently within a single patient, as well as the management of multiple chronic diseases in a single patient.[15]
While many internal medicine physicians choose to subspecialize in specific organ systems, general internal medicine specialists do not necessarily possess any lesser expertise than single-organ specialists. Rather, they are specifically trained t