internist
physician with medical specialty internal medicine; is skilled in the management of patients who have undifferentiated or multi-system disease processes; cares for hospitalized and ambulatory patients
endocrinologist
scientist who studies the endocrine system
rheumatologist
physician with training in rheumatic diseases
hematologist
physician with medical specialty hematology
cardiologist
physician who specializes in cardiology
geriatrician
medical specialist in the care of the elderly
gastroenterologist
physician, specialised for gastroenterology