Cardiology, hospitalist medicine,infectious dz, gastroenterology, internal medicine

In the U.S. the subspecialties of internal medicine are well integrated in the overall discipline of internal medicine and each one is also unique. The American Board of Internal Medicine at present certifies 16 unique subdisciplines, which are, in order from the largest to the smallest: cardiology (14,000 certified cardiologists), gastroenterology (10,000 certified), pulmonary disease (9000 certified), critical care medicine (6500 certified), hematology, oncology, nephrology, infectious diseases, allergy and immunology, endocrinology, rheumatology, geriatrics, sport medicine, adolescent medicine...