According to the DSM-IV-TR (2000), hypochondriasis is the “preoccupation of having, or the idea that one has, a serious disease based on the person’s misinterpretation of bodily sensations.”
In addition to this, the person believes that he or she is ill despite the results of medical testing, and that belief leads to impairment in social, occupational, or other types of functioning.
Further, for diagnosis of hypochondriasis, the person must not have a delusional disorder, and the person’s belief that he or she is ill must be ongoing for at least 6 months.
OCD is different from hypochondriasis in that, even if one of the foci of the OCD is medical concerns, individuals will also have other obsessions and unrelated compulsions, such as compulsively straightening things.
If the focus is only on illness or disease, then hypochondriasis is the appropriate diagnosis.