Hepatology is the medical specialty dealing with the diagnosis and treatment of diseases of the liver and its associated organs such as the gall bladder and pancreas, as well as the structures that connect them. It is a branch of internal medicine. Once merely a sub-specialty of gastroenterology, it is now considered a medical specialty in its own right. The concept of diseases specific to the liver dates back to antiquity, and Hippocrates wrote about liver diseases in 400 B.C.E.