As opposed to family medicine, internal medicine involves a physician becoming a specialist in the medical problems that befall just adults. Frequently referred to as internists, these doctors often branch off into more specific subspecialties of internal medicine, from cardiolology and hematology to nephrology and sports medicine. In all, as many as 20 focused disciplines allow doctors to further specialize within this fairly generalized medical discipline to offer patients and even other doctors the best advice.
According to the American College of Physicians (ACP), the field and subspecialties of internal medicine began when German doctors in the late 19th century started using laboratory-based methods to bolster ordinary patient care. Within a few decades the field had spread to the west. In 2011, the ACP recognized 13 areas of specialization, starting with adolescent medicine, allergies and immunology, cardiology for heart disorders, and endocrinology for glandular disorders like diabetes. More specialties include gastroenterology for digestive issues, geriatric care, hematology for blood diseases and disorders, infectious diseases, and nephrology for the kidneys. The rest are oncology for cancer, pulmonology for respiratory problems, rheumatology for arthritis, and sports medicine.
This is not a complete list of all the subspecialties of internal medicine, though. Lesser known are seven more subspecialties for which the American Board of Internal Medicine (ABIM) certifies doctors under the category of internal medicine. The organization certifies doctors in four separate cardiology subspecialties, though some consider these sub-subspecialties of cardiology: trauma and transplant cardiology, cardiovascular disease, interventional cardiology and cardiac electrophysiology. Internists are also certified by the ABIM in sleep medicine and transplant hepatology. Many also would add to this list the subspecialty of hospital medicine in which doctors subspecialize in the ailments and injuries that most often require hospitalization.
A common path for a patient is to start with a primary care physician, or family doctor, who might then refer the patient to an internist for help with diagnosis or treatment options. This internist may then refer the patient to a local expert in one of the subspecialties of internal medicine, or more than one. For instance, an elderly patient who contracts cancer might have a family doctor, an oncologist and a geriatric specialist, who just might send the patient to a pulmonologist, if a problem develops with the patient's breathing.
To legally practice these disciplines, most countries require a medical degree and passage of a certification exam from an accredited body, such as the American Board of Internal Medicine for U.S. doctors. For renewal, doctors are typically required to attend regular training to keep up on the latest research, techniques and treatment options. Some of these physicians have certification in just one of the subspecialties of internal medicine. Others are certified in a handful of areas to offer more informed generalized care.