Internal medicine or General medicine (in Commonwealth nations) is the medical specialty dealing with the prevention, diagnosis, and non-surgical treatment of diseases in adults. Physicians specializing in internal medicine are called internists or physicians in Commonwealth nations. The therapeutic range of Internal Medicine includes a wide range of respiratory, haematology, gastrointestinal, endocrine, cardiovascular, nervous, musculoskeletal and urogenital disorders as well as the metabolic and biochemical disorders and infectious diseases. Internists are especially skilled in the management of patients who have undifferentiated or multi-system diseases. Internists care for hospitalized and ambulatory patients and play a major role in teaching and research.