What is an Internist?


An internist is a physician who is trained in internal medicine. Internists work with adult patients to help them manage and treat an array of medical conditions.


According to the website for the American College of Physicians, Internists are “specialists who apply scientific knowledge and clinical expertise to the diagnosis, treatment, and compassionate care of adults across the spectrum from health to complex illness.”  (About ACP)


Internal Medicine developed as a unique medical specialty in the 1880s, due to a growing interest in employing scientific knowledge and diagnostic approaches within the medical field (Fordtran, Armstrong, Emmett, Kitchens, & Merrick, 2004). Today, Internists can be found working throughout the healthcare system, as hospital based consultants, as researchers, and as primary care physicians. However, all Internists are united by their rigorous training, their scientific approach to treatment, and their focus on providing care to adult patients.


What is the difference between an Internist, a Primary Care Provider, and a Family Medicine Doctor?


For many members of the general public, significant confusion exists regarding the difference between “internists,” “primary care providers” and “family medicine doctors.”


The phrase “primary care provider” (PCP) refers to a general category of practitioner, which may include an internist, a nurse practitioner, a family care doctor, or a physician’s assistant. PCPs serve as the initial contact between patients and the health care system. They are also usually the provider with whom most patients will interact the most.  Health insurance companies will also frequently require a sick patient to see their PCP first in order to be referred to an appropriate specialist (Holl, 2016).


While internists only treat adult patients, a family doctor is qualified to see patients of any age, from children to elderly adults. Family doctors undergo a similar training program to internists: after medical school is complete, they must undergo three years of medical residency. (ACP, Family Medicine vs. Internal Medicine).


History of the Term “Internal Medicine”


The term “internal medicine” is derived from the 19th century German phrase “innere medizin,” which was used in Germany to refer to physicians who combined clinical practice with scientific experimentation.  It may actually be the case that the word “internal” in “internal medicine” does not refer to the inside the body at all, but rather to a physician who gets to the inside of a clinical problem by using knowledge that comes from experimental science.” (Fordtran, Armstrong, Emmett, Kitchens, & Merrick, 2004)


In the United States, the first known use of the phrase came in 1895 when Dr. William Osler gave an address to the Association of American Physicians. (Fordtran, 2004) Two years later in an 1897 address, Osler would famously argue the importance of internal medicine by stating that internists “cannot be called specialists, but bear without reproach the good old name physician: the physician proper”, reassuring his audience of physicians that “the opportunities are still great, that the harvest truly is plenteous, and the labourers scarcely sufficient to meet the demand.”(Bryan, 2015)




Dr. William Osler (1849-1919)


Dr. William Osler is regarded by many as not only as “the father of internal medicine,” but as one of the most influential physicians in modern history. (Bryan 2015) Osler was born in a rural Canadian town in 1849.  His parents were Anglican missionaries who had recently emigrated from England and William was the eighth of their nine children (Profiles in Science). In 1867, he entered the University of Trinity College in Toronto, with the intention of studying for the ministry. However, with encouragement from his mentor Dr. James Bovell, Osler soon switched to the study of medicine (Profiles in Science). In 1870, Osler left Trinity to complete his medical studies at McGill University. He obtained his medical and surgical degrees from McGill in 1872. Osler then spent the next two years studying in Europe, traveling from London to Berlin and Vienna and working with some of the continent’s greatest physicians, including Rudolf Virchow and John Burdon Sanderson. In 1874, he returned to Montreal to accept a position in the McGill University Faculty of Medicine. He stayed at McGill for several years. During this period, he was also appointed as an attending physician at Montreal General Hospital.


In 1884 he moved to the United States to take a position as Chair of Clinical Medicine at the University of Pennsylvania School of Medicine. He would work in Philadelphia for the next five years, immersed in teaching and his local clinical practice. The latter attracted a diverse range of patients from across the broader Pennsylvania and New Jersey area, including, notably, the poet Walt Whitman. (Profiles in Science)


 In 1889, Osler was named Physician in Chief at the recently opened Johns Hopkins Hospital and later, Professor of Theory and Practice of Medicine at the brand new Johns Hopkins School of Medicine. As one of the founding faculty members at Johns Hopkins,  Osler seized the opportunity to create “America’s first modern medical training program” (Profiles in Science) basing it primarily on the German model. In Osler’s program, third year students worked outpatient clinics, while fourth years students were required to work in hospitals, rotating every two months between different specialities.  Through this model, students were able to gain significant clinical experience in a variety of specialities. Osler’s program stands as the first time medical students were brought out of the classroom and to learn at the bedside. (Profiles in Science)


In 1892, Osler published “The Principles and Practice of Medicine,” a widely respected medical textbook which further increased his national and international profile as a brilliant physician. The textbook remained in active use for decades and is still considered to be a classic of medical literature. To date, it has gone through sixteen different editions (Launer, 2016).


Osler and his family moved to England in 1905 in order to accept a position as Regius Professor of Medicine at the University of Oxford.  In 1911, King George the V awarded him a baronet for his scientific and medical contributions. However, tragedy struck in 1917 when Osler’s son was killed on the battlefields of World War I.  Osler himself would die just 2 years later.


Osler made significant contributions to the medical literature, publishing more than 1300 articles over the course of his life, touching on almost every branch of medicine (Profiles in Science). However, for many, he is most powerfully remembered as the quintessential humanist physician, who put his relationships with students and patients first (Profiles in Science, Launer, 2016). He was known as much for his brilliance as for his warm bedside manner and his lifelong fondness for practical jokes (Launer, 2016).  Osler once stated, "I desire no other epitaph than the statement that I taught medical students in the wards, as I regard this as by far the most useful and important work I have been called upon to do.” (Profiles in Science)


Osler was the most well-known physician of his time, and he used his notoriety to advocate on behalf of social causes, including support for racial equality and for the inclusion of more women students in medical schools (Launer, 2016). He was also an avid book collector throughout his life and built up a valuable medical and scientific collection with more than 8,000 items (Launer, 2016).  After his death, the entire library was donated to McGill.  Osler’s ashes and those of his wife, are currently interred alongside the collection (McGill, About William Osler).


The American College of Physicians and the Rising Influence of Internal Medicine


The field of Internal Medicine has enjoyed a prominent place in the American healthcare system, in large part due to the success of its membership organization, the American College of Physicians (ACP).  With 152,000 members worldwide, the ACP is currently the “largest medical speciality organization” in the world. (ACP, Who We Are)


In 1913, the German American physician Heinrich Stern attended a meeting of the Royal College of Physicians in London and became convinced of the importance of establishing a similar body in the United States in order to “facilitate scientific intercourse among physicians interested in internal medicine.” (Bryan, 2015) In 1915, working together with six other internal medicine practitioners, Stern founded the ACP to be an American organization that was oriented towards promoting the field of internal medicine, both within the United States and abroad. (Bryan, 2015) 1920 would see the founding of the ACP’s medical journal, the Annals of Medicine. By 1927, the name had been changed to the Annals of Internal Medicine, which is still considered today to be the leading journal of internal medicine worldwide. (Fordtran et al., 2004)


In 1936, the ACP would partner with the American Medical Association to create the American Board of Internal Medicine.(ABIM) The mission of the ABIM was to  develop comprehensive standards for internal medicine. Medical students would henceforth be required to sit for grueling oral and written exams in order to receive their certification as practicing internists. (Fordtran et al., 2004)  It was hoped that these reforms would help raise the profile of American internists so that training in the United States system would have an equivalent cache to medical training elsewhere in Europe. (Fordtran et al., 2004) World War II also led to an increased level of importance for the ABIM and other medical speciality boards, because the army medical corps required that all of their doctors be board certified. (Fordtran et al., 2004)


After the war, the establishment of the National Institutes of Health(NIH) further aided in the growth of internal medicine. Scientific advancements had made a decisive impact on the course of the war. Consequently, a new flood of grant money began to pour into medical schools across the country.  As members of a field that was closely associated with academic output and scientific experimentation, internal medicine departments would often receive the lion’s share of the money. (Fordtran et al., 2004)




Challenges to Internal Medicine As A Field


Over the course of the twentieth century, Internal medicine departments tended to foster their images as being brutally demanding centers of “uncompromising excellence,” that attracted the brightest and most driven medical students from around the country. (Bryan, 2015)  An article in the medical journal The Lancet recalls a story from Duke University:


The story goes that on one occasion the physician Eugene A Stead of Duke University, who has been called the last professor of medicine in the Oslerian mould, heard a resident present a case from the previous evening and asked: “What did the spinal fluid show?” The exhausted resident chirped that he’d been up most of the night, that other patients needed equal attention, and that the case was extremely confusing. “Doctor”, Stead lectured, “You’re telling me that life is hard. I already know that. I want to know what this patient’s spinal fluid showed.”  (Bryan, 2015)



Towards the end of the 20th century, the discipline of internal medicine looked to be in somewhat of a crisis.  (Nolan, 1998) The growth of family medicine presented an option for primary care that was more intuitively named and thus appealing to the general public.  In addition, the scope of general internal medicine was becoming increasingly narrowly defined, due to the creation of new specialties such as emergency medicine that focused on clinical areas which might previously have been under a general internist’s purview, (Nolan, 1998) Many wondered if internal medicine might dissolved into a series of subspecialties instead of continuing as a coherent discipline in its own right. (Bryan, 2015)


 However, the historian Rosemary Stevens has suggested four reasons why internal medicine has not merely stayed relevant, but has actively flourished over the second half of the century. First, Stern argues that internists have had “ a proven track record of resilient adaptation to change.” For example, during the 1990s, many internists working within a hospital setting adopted the name “hospitalists,” in order to offer more clarity about their position and role.  Secondly, Stevens suggests that internists provide the vast majority of primary care services across the United States, making them an indispensible part of the healthcare workforce. Third, internal medicine encompasses a spectrum of care, leading to many internists with positions high up in healthcare organizations. Finally, Stevens argues that internal medicine has at times served as a conscience for the broader medical profession. (Bryan, 2015)




The path to becoming an internist is a long one. Prospective internists must first attend four years of medical school. Following this, they are required to complete a three year long categorical residency program, spending at least 70% of that time working in a hospital setting.  (Internal Medicine Interest Group) “Categorical residency programs” offer full residency training, after which a student can immediately apply for board certification as a general internist. (Categorical Vs. Primary)  In the United States, around half of all internists choose to become certified as general internal medicine practitioners.   (ACP, About Internal Medicine) General internists often go on to pursue careers as consultants or primary care providers, working from a variety of settings, including hospitals and private practice.


Other internists may choose to continue their training in a sub-specialty. (ACP, Structure)  Subspecialty training typically takes the form of a one to three year fellowship, completed after the residency is finished. The length of the fellowship varies depending on the speciality and whether or not the student is pursuing an academic career or a career as a practicing clinician, with practicing clinicians typically spending longer in training. (Internal Medicine Interest Group)


Students may also elect to complete a dual residency program that combines internal medicine with training in a subspecialty. This option allows residents to complete their training in a shorter amount of time. Common combinations for dual residency programs include internal medicine with pediatrics and internal medicine with emergency medicine. (ACP, Subspecialties)


According to the American College of Physicians, internists can subspecialize in any of the following areas (ACP, Subspecialties):


Allergy and immunology:  This subspecialty focuses on immune system disorders, including allergic reactions in the eyes and respiratory system, adverse reactions to drugs, and more. Allergy and immunology fellowships are typically two years each, following the completion of a categorical Internal medicine residency. However, a three year combined fellowship in allergy, immunology and rheumatology is also available. When training is completed, board certification is available through the American Board of Internal Medicine (ABIM)


Cardiovascular:  This subspecialty focuses on diseases related to the cardiovascular system, including all aspects of heart disease as well as circulation disorders. Cardiovascular fellowships are three years each, after which an internist may apply for certification through the ABIM.


Endocrinology, Diabetes, and Metabolism: This subspecialty focuses on the management of glandular and metabolic disorders, including diabetes. An endocrinology fellowship is typically completed in two years, after which certification is available via the ABIM.


Gastroenterology: This is a subspecialty which manages disorders of the gastrointestinal system, liver, and gall bladder. Gastroenterology fellows may also receive training in nutrition and nutrition related diseases. Gastroenterology fellowships are usually three years long, after which an internist will be eligible to apply for ABIM certification.


Hematology: Specialists in hematology manage disorders related to blood, lymphatic systems, and bone marrow. A hematology fellowship consists of two years of training prior to becoming eligible for board certification through the ABIM. However, residents frequently opt for a joint three year program in hematology and oncology, a pairing which provides the necessary training to manage an array of related disorders.


Infectious Disease: This subspecialty focuses on the management of infectious disease, including bacterial, viral, fungal, and parasitic infections. Infectious disease fellowships generally take 2 years to complete, after which an intern can apply for ABIM certification.


Nephrology: This subspecialty manages disorders related to the kidneys.  Fellowships in nephrology are typically two years long, after which an intern is eligible to apply for board certification through the ABIM.


Oncology: Oncology subspecialists focus on the management and treatment of neoplasms, or abnormal growths in the body. Oncologists may treat benign neoplasms, or they may treat malignant neoplasms, which are cancerous growths. Oncology fellowships generally last for two years. However, some providers choose a joint oncology and hematology fellowship, which takes three years to complete. As with other subspecialties, upon completion of the fellowship, oncologists are also able to apply for certification through ABIM.


Pulmonary Disease: This subspecialty is concerned with the management of the lungs and respiratory system. Because pulmonologists are often called upon to oversee the treatment of patients who have undergone respiratory failure, pulmonology fellowships are often coupled with training in critical care medicine.  A pulmonology fellowship by itself can take two years to complete, while a combined program will take three years.  At the completion of their fellowship, a newly trained physician can apply via the ABIM for separate certifications for pulmonology and critical care medicine.


Rheumatology: The subspecialty of rheumatology is concerned with disorders related to the joints and musculoskeletal system. A rheumatology fellowship takes two years to complete, but residents can also choose to apply for a three year long joint fellowship in allergy, immunology and rheumatology.


Internists and other physicians (such as pediatricians or family medicine doctors) may also choose to pursue additional training in one of the following areas:


Adolescent Medicine: Adolescent medicine focuses on the constellation of physical, mental, emotional and behavior disorders which are specific to adolescents and young adults. Adolescent medicine fellowships require an additional two years of training.  Certification is available through the ABIM, the American Board of Family Medicine and the American Board of Pediatrics.


Critical Care Medicine: Critical care training prepares physicians to diagnose and treat patients in need of intensive care.  Internists may choose to complete a three year joint fellowship to receive training in critical care medicine and pulmonology. Alternatively, internists may complete a separate two year fellowship at the conclusion of their residency. There is also an option to complete a two year fellowship in either advanced general internal medicine or another subspecialty, followed by a one year fellowship in critical care medicine.  Certification is available and jointly administered via the ABIM, the American Board of Surgery, and others.


Geriatric Medicine:  Geriatric medicine programs offer physicians the opportunity to be trained in the care of older adults. Geriatric fellowship program last for one year and board certification is available.


Hospice and Palliative Medicine: Palliative care physicians help patients dealing with serious illness to relieve their pain and other symptoms. Hospice care physicians offer similar care for patients who have a terminal diagnosis.  Hospice and Palliative Medicine training can be completed in a one year post residency fellowship training. Certification is also available through the boards of nine medical disciplines, including internal medicine, emergency medicine, family medicine, and others.


Sleep Medicine: Sleep medicine programs train physicians to manage sleeping disorders and associated conditions.  Training programs are generally year-long post residency fellowships. Sleep Medicine certification is available and is jointly administered by the ABIM, the American Board of Family Medicine, and several other related organizations.


Sports Medicine: As the name suggests, sports medicine training programs prepare physicians to treat sports injuries and related problems.  One year sports medicine fellowships are available after the completion of a three year internal medicine residency. Internists can then apply for certification via the Sports Medicine Certification Program.


Women’s Health:  Training programs in women’s health can vary substantially in focus and may explore a range of gender health issues such as sexual violence, maternal health, menopause, or others. Certain internal medicine residency programs offer a women’s health track as part of the three year training program. Residents can also apply for a one to two year long women’s health fellowship at the conclusion of their residency.  There is no separate certification available in women’s health through the ABIM.


The Ongoing Importance of Internal Medicine:


Internal medicine continues to suffer from what historian Rosemary Stevens has called, “definitional ambiguity,” with few members of the general public being clear on precisely what an internist does or when it would be necessary to see one. (Bryan, 2015) In answer to this question, the ACP website has stated that “internal medicine is perhaps best defined by its unique approach to medicine and its ‘scientific attitude’, rather than by a specific group of patients being cared for, the practice setting, or research activity being pursued.”  (ACP, About Internal Medicine)


In the first decades of the 21st century, internists continue to play vital roles in the American healthcare system, serving not only as primary care providers for a large percentage of the population, but as consultants, diagnosticians, and researchers, pushing the field of medicine onward into a new era. 





About William Osler. (n.d.). Retrieved September 03, 2017, from https://www.mcgill.ca/library/branches/osler/oslerbio


American College of Physicians | Internal Medicine | ACP. (n.d.). Retrieved September 03, 2017, from https://www.acponline.org/


About Internal Medicine: https://www.acponline.org/about-acp/about-internal-medicine


Internal Medicine vs. Family Medicine: https://www.acponline.org/about-acp/about-internal-medicine/career-paths/medical-student-career-path/internal-medicine-vs-family-medicine


History: https://www.acponline.org/about-acp/who-we-are/history


Subspecialties of Internal Medicine: https://www.acponline.org/about-acp/about-internal-medicine/subspecialties


Structure of Internal Medicine Residency Training: https://www.acponline.org/about-acp/about-internal-medicine/career-paths/medical-student-career-path/structure-of-internal-medicine-residency-training


Bryan, C. S. (2015). Osler redux: the American College of Physicians at 100. The Lancet, 385(9979), 1720-1721.


Categorical vs. Preliminary. (n.d.). Retrieved September 03, 2017, from http://residency.wustl.edu/RESIDENCIES/Pages/CategoricalvsPreliminary.aspx


Fordtran, J. S., Armstrong, W. M., Emmett, M., Kitchens, L. W., & Merrick, B. A. (2004, January). The history of internal medicine at Baylor University Medical Center, part 1. Retrieved September 03, 2017, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1200637/


Holl, K. (2016, August 31). Guide to Primary Care Practitioners (PCP), Family Doctors, and Internists. Retrieved September 03, 2017, from http://www.healthline.com/health/types-of-doctors


Internal Medicine Interest Group. (2011, February 24). Retrieved September 03, 2017, from https://www.med.unc.edu/imig/about


Launer, J. (2016). The career of William Osler. Postgraduate medical journal, 92(1094), 751-752.


Letelier, L. M., Valdivieso, A., Gazitúa, R., Echávarri, S., & Armas, R. (2011, August). [A consensus definition of internal medicine and the internist]. Retrieved September 03, 2017, from https://www.ncbi.nlm.nih.gov/pubmed/22215341


Nolan, J. P. (1998). Internal medicine in the current healthcare environment: a need for reaffirmation. Annals of internal medicine, 128(10), 857-862.


Profiles in Science: The William Osler Papers. (n.d.). Retrieved September 03, 2017, from https://profiles.nlm.nih.gov/GF/


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