If the item is a medical fact, then no. If it is an opinion, then you are entitled to add your comment or any evidence that you have to refute that opinion. If the opinion is scurrilous or defamatory you are entitled to complain about the person who wrote it
Also there is not one medical record as such. Your GP keeps records, any hospitals or clinics that you have attended may keep separare records, as may any other kinds of services. STD clinic records are particularly closely guarded