A patient rarely has a single, isolated disease. The situation is usually much more complex since the different parts of the human organism and metabolism interact with each other and follow several feedback patterns. These interactions and feedback patterns become more important with the addition of the external environment. When a disease is present, the first steps of the medical diagnosis should be to research and to determine whether another disease interacts with ("Censors") or changed the significant symptoms, syndromes, or results of the laboratory tests of the first disease. Understanding of this interaction and the appropriate reasoning is based on a type of non-monotonic logic. We will try, within this paper, to see the effect of two diseases on each other. One important part of the effect of two diseases on each other is the entrancing effect of what we call "Censors." In addition, causal reasoning, reasoning by analogy, and learning from precedents are important and necessary for a human-like expert in medicine. Some aspects of their application to thyroid diseases, with an implemented system, are considered in this paper.