Even though these persons are regularly visiting doctors (from different fields and usually also at different places) and have careful medical examinations and explanations of the symptoms, the occupation with the fear of diseases remains. If the results or statements of the doctors are not completely clearn and unambiguous, they can sometimes even strengthen the uncertainty and anxiety. The sentence "We can not find anything pathological " could raise thoughts as that the examination was not done carefully enough or that it must be a very rare disease.
Reinsurance: To be sure not to suffer from anything undiagnosed the persons with hypochondria often also visit hospitals or medical emergency services to have an EKG or other more complex investigations done. The calming results do not help for very long though and the fear is soon returning.
Therefore hypochondria is concidered as an anxiety disorder . The anxiety, the regular examination of symptoms and the wrong interpretion of normal physical reactions (e.g. heartrate, breathing, muscle strains) causes thoughts of helplessness, fear or even panic. The onset can be caused by earlier, actual physical illness in the person regarded or in a friend or family member. (e.g. a colleague's heart attack).
Contrary to what people might believe, the person with hypochondria does not make up/pretend or simulate an illness. To be diagnosed with hypochondria the person must have been suffering for a period of at least 6 months. Unfortunately many of the people do not realize that they are suffering from an anxiety disorder and not from a physical illness. It is also difficult to get insight and help with the disorder since persons with hypochondria usually visit many different doctors which makes it difficult to get continuous support and assistance.